{"gene":"BAIAP2","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2000,"finding":"Activated Rac binds to the N-terminal domain of IRSp53, and the C-terminal SH3 domain of IRSp53 binds to WAVE, forming a trimolecular Rac–IRSp53–WAVE complex that is essential for Rac-induced membrane ruffling.","method":"Co-immunoprecipitation, ectopic expression, domain-binding assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays plus functional rescue experiments, replicated across multiple subsequent studies","pmids":["11130076"],"is_preprint":false},{"year":2001,"finding":"Cdc42 binds to a partial CRIB motif in IRSp53, relieving an intramolecular autoinhibitory interaction between the CRIB-containing central region and the N-terminal domain, thereby allowing the SH3 domain to recruit Mena; the resulting IRSp53–Mena complex promotes filopodia formation.","method":"Affinity chromatography, co-immunoprecipitation, dominant-negative expression, filopodia formation assay in fibroblasts","journal":"Current Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (affinity chromatography, Co-IP, dominant-negative rescue) in a single study, widely replicated","pmids":["11696321"],"is_preprint":false},{"year":1999,"finding":"The SH3 domain of BAIAP2/IRSp53 directly binds to a proline-rich cytoplasmic fragment of BAI1 (brain-specific angiogenesis inhibitor 1), and co-expression with BAI1 recruits BAIAP2 to the cytoplasmic membrane.","method":"Yeast two-hybrid, in vitro binding assay, double-color immunofluorescence in COS-7 cells","journal":"Cytogenetics and Cell Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid confirmed by in vitro binding and co-localization, single lab","pmids":["10343108"],"is_preprint":false},{"year":2000,"finding":"The proline-rich FH1 domain of mDia1 binds the SH3 domain of IRSp53/BAIAP2 in a GTP-Rho-dependent manner, identifying IRSp53 as a downstream effector of mDia1.","method":"Pulldown assay, co-immunoprecipitation with GTP-Rho","journal":"Biochemical and Biophysical Research Communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct pulldown with GTPase-dependency shown, single lab, single method","pmids":["10814512"],"is_preprint":false},{"year":2002,"finding":"The SH3 domain of IRSp53 interacts with a proline-rich sequence in ProSAP/Shank family members, and the IRSp53–Shank complex is co-immunoprecipitated from rat brain membranes; active Cdc42 regulates coprecipitation of IRSp53 with Shank1.","method":"Yeast two-hybrid, Co-IP from rat brain, mutational analysis, co-expression in COS cells","journal":"Journal of Neurochemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — interaction confirmed by Co-IP from native brain tissue plus mutagenesis to map binding site, replicated by two independent labs","pmids":["12421375","12504591"],"is_preprint":false},{"year":2002,"finding":"The SH3 domain of IRSp53 interacts with proline-rich residues 911–940 of Shank1; co-expression of Shank1 with IRSp53 in HEK cells prevents IRSp53 targeting to filopodia, and this redistribution is regulated by active Cdc42.","method":"Yeast two-hybrid, overlay assay, co-expression in HEK cells, pulldown with GTPase","journal":"Molecular and Cellular Neurosciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — overlay assay plus cellular localization assay, single lab, no reciprocal Co-IP from tissue","pmids":["12504591"],"is_preprint":false},{"year":2003,"finding":"IRSp53 localizes specifically to the tips of protruding lamellipodia and filopodia via its N-terminal Rac-binding domain, and co-localizes with WAVE2 at these sites during protrusion.","method":"Live-cell imaging of EGFP-tagged IRSp53 and DsRed-WAVE2, antibody labeling, deletion mutant analysis","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — live-cell imaging with multiple deletion constructs to map localization determinant, co-localization with WAVE2 demonstrated in two conditions","pmids":["12734400"],"is_preprint":false},{"year":2004,"finding":"IRSp53 directly binds Eps8 via its SH3 domain and the N-terminal proline-rich region of Eps8; the IRSp53–Eps8 complex forms at the leading edge of motile cells and synergistically activates Rac by reinforcing formation of the Eps8/Abi-1/Sos-1 GEF complex.","method":"Co-immunoprecipitation, direct binding assay, FRET analysis in live cells, invasion/motility assays","journal":"Cancer Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP of endogenous proteins plus direct binding, FRET confirmation of complex at leading edge, functional rescue, replicated in subsequent studies","pmids":["15289329"],"is_preprint":false},{"year":2005,"finding":"The crystal structure of the IRSp53 IMD (I-BAR domain) reveals a zeppelin-shaped coiled-coil dimer; mutagenesis of conserved basic residues at the dimer tips abrogates F-actin bundling in vitro and filopodia formation in vivo, establishing that IMD-mediated actin bundling is required for filopodia induction.","method":"X-ray crystallography, analytical ultracentrifugation, in vitro actin bundling assay, site-directed mutagenesis, filopodia formation assay","journal":"The EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus in vitro reconstitution of actin bundling plus mutagenesis and in vivo filopodia assay in one study","pmids":["15635447"],"is_preprint":false},{"year":2005,"finding":"Tiam1 binds IRSp53 and directs it toward Rac (rather than Cdc42) signaling by enhancing IRSp53 binding to active Rac and the WAVE2 scaffold; IRSp53 depletion prevents Tiam1-dependent lamellipodia formation.","method":"Co-immunoprecipitation, RNAi knockdown, lamellipodia formation assays, PDGF stimulation","journal":"Molecular and Cellular Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus RNAi-based functional rescue, single lab","pmids":["15899863"],"is_preprint":false},{"year":2006,"finding":"IRSp53 optimizes WAVE2 complex-mediated Arp2/3 activation in a Rac- and PIP3-dependent manner on membranes; WAVE2 complex isolated from the membrane fraction (but not cytosol) is fully active in an IRSp53-dependent manner.","method":"RNAi knockdown, in vitro Arp2/3 activation assay with purified proteins and PIP3-liposomes, membrane fractionation","journal":"The Journal of Cell Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified WAVE2 complex, IRSp53, Rac, and PIP3-liposomes; multiple conditions tested; single lab","pmids":["16702231"],"is_preprint":false},{"year":2006,"finding":"Eps8 has intrinsic actin cross-linking activity and synergizes with IRSp53 for actin bundling in vitro; Cdc42 controls the cellular distribution of the IRSp53–Eps8 complex; Cdc42-induced filopodia require both IRSp53 and Eps8.","method":"In vitro actin bundling assay, Co-IP, RNAi knockdown, filopodia formation assay","journal":"Nature Cell Biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of actin bundling plus RNAi loss-of-function with specific filopodia phenotype, replicated","pmids":["17115031"],"is_preprint":false},{"year":2006,"finding":"The RCB/IMD domain of IRSp53 induces membrane deformation (small buds) on liposomes in a Rac-dependent manner via its convex surface, opposite to the invaginations produced by BAR domains; this activity is independent of actin.","method":"Liposome deformation assay, crystal structure of RCB/IMD, mutational mapping of membrane-binding residues, cellular expression of domain constructs","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural data plus in vitro liposome deformation and Rac-dependency mapping, single lab","pmids":["17003044"],"is_preprint":false},{"year":2007,"finding":"The N-terminal IMD (I-BAR domain) of IRSp53 directly binds PI(4,5)P2-rich membranes and deforms them into tubular structures with curvature opposite to BAR domains (negative curvature/outward protrusion); the membrane-deforming activity of the IMD, rather than its actin-bundling or GTPase-binding activities, is critical for filopodia/microspike induction.","method":"In vitro membrane tubulation assay with PI(4,5)P2 liposomes, electron microscopy, mutagenesis, cellular filopodia assay","journal":"The Journal of Cell Biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with defined lipid compositions plus mutagenesis separating activities, widely replicated","pmids":["17371834"],"is_preprint":false},{"year":2007,"finding":"Synaptopodin directly binds IRSp53 and suppresses Cdc42:IRSp53:Mena-initiated filopodia formation by blocking the binding of Cdc42 and Mena to IRSp53 in kidney podocytes.","method":"Co-immunoprecipitation, pulldown, filopodia formation assay, siRNA knockdown, pharmacological Mena inhibition in vivo","journal":"The American Journal of Pathology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding confirmed by pulldown plus functional loss-of-function in cells and in vivo, single lab","pmids":["17569780"],"is_preprint":false},{"year":2008,"finding":"IRSp53 directly interacts with N-WASP via its SH3 domain; the I-BAR domain alone induces membrane protrusions lacking actin ('partial filopodia'), while full filopodia require SH3-domain partners (N-WASP and Mena/VASP); Mena/VASP but not N-WASP Arp2/3-activation activity is required for IRSp53-induced filopodia.","method":"Co-IP, RNAi knockdown in N-WASP KO and Mena/VASP KO fibroblasts, expression of domain mutants, filopodia reconstitution assay","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO fibroblast reconstitution plus multiple domain mutants, two independent KO cell lines tested","pmids":["18448434"],"is_preprint":false},{"year":2008,"finding":"Par1b directly phosphorylates IRSp53 on S366 (and indirectly on S453/3/5), and a Par1b phosphorylation-deficient IRSp53 mutant rescues cell spreading and lumen polarity defects in Par1b-overexpressing MDCK cells, placing IRSp53 downstream of Par1b in cell-ECM signaling.","method":"In vitro kinase assay with cell lysates, site-directed mutagenesis, RNAi knockdown, rescue assays in MDCK cells","journal":"The Journal of Cell Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct phosphorylation demonstrated in cell lysates with mutational validation and functional rescue, single lab","pmids":["21282462"],"is_preprint":false},{"year":2008,"finding":"LIN7 recruits IRSp53 to tight junctions via its PDZ domain; loss of LIN7 prevents TJ localization of IRSp53 and reduces Rac1 activation, causing defects in TJ assembly and epithelial cyst polarization.","method":"Dominant-negative LIN7 expression, shRNA knockdown, immunofluorescence, Co-IP, Rac1 activation assay","journal":"Traffic","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic tools (dominant-negative, shRNA) with functional phenotypes, single lab","pmids":["19054385"],"is_preprint":false},{"year":2008,"finding":"Tyrosine 310 in the central unstructured region of IRSp53 is the primary site of phosphorylation downstream of the insulin receptor; the N-terminal IMD domain is required for efficient tyrosine phosphorylation but is not itself phosphorylated.","method":"Truncation and point-mutant analysis with insulin/EGF stimulation, Western blotting for phosphotyrosine","journal":"European Journal of Cell Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic mutagenesis to map phosphorylation site, single lab","pmids":["18417251"],"is_preprint":false},{"year":2009,"finding":"IRSp53 family members directly interact with both EHEC Tir (via residues 454–463) and EspFU, colocalizing with EspFU and N-WASP in actin pedestals; loss of IRSp53 abrogates EHEC actin assembly, identifying IRSp53 as the missing host factor linking Tir to EspFU.","method":"Co-IP, direct binding assay, genetic loss-of-function (IRSp53 KO cells), immunofluorescence colocalization","journal":"Cell Host & Microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding plus genetic KO with specific actin-assembly phenotype, replicated with dissection of Tir binding residues","pmids":["19286134"],"is_preprint":false},{"year":2009,"finding":"IRSp53 knockout mice display a selective increase in NMDA receptor-mediated synaptic transmission (but not AMPA) and markedly enhanced LTP, establishing that IRSp53 negatively regulates NMDA receptor function at excitatory synapses.","method":"IRSp53 knockout mice, electrophysiology (AMPA/NMDA ratio, LTP), immunoelectron microscopy of PSD","journal":"The Journal of Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with electrophysiological phenotype, replicated by multiple independent labs","pmids":["19193906"],"is_preprint":false},{"year":2009,"finding":"Kank specifically inhibits the binding of IRSp53 to active Rac1 (but not Cdc42), thereby suppressing IRSp53-dependent lamellipodia formation without affecting filopodia.","method":"Co-IP, direct binding competition assay, RNAi double-knockdown, lamellipodia/filopodia formation assays","journal":"The Journal of Cell Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP competition assay plus double-KD rescue experiment, single lab","pmids":["19171758"],"is_preprint":false},{"year":2009,"finding":"14-3-3 binding to phosphorylated residues T340 and T360 (between the CRIB and SH3 domains of IRSp53) inhibits SH3-domain interactions with WAVE2 and Eps8 and blocks Cdc42-GTP binding, extending filopodium lifetimes when these sites are mutated.","method":"Phosphorylation mapping, Co-IP, SH3 domain-swapping, live-cell filopodia dynamics imaging","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — phospho-site mapping plus domain-swapping plus live-cell functional imaging, single lab","pmids":["19933840"],"is_preprint":false},{"year":2009,"finding":"Postsynaptic Shank proteins compete with Eps8 for binding to IRSp53, blocking Eps8-IRSp53-dependent actin bundling; IRSp53 KO mice show decreased PSD size and increased NMDA receptor subunits at the PSD.","method":"IRSp53 KO mice, competitive binding assay, electrophysiology, LTP measurement","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — competitive binding with multiple proteins plus genetic KO mouse with electrophysiological and ultrastructural phenotypes, multi-method","pmids":["19208628"],"is_preprint":false},{"year":2009,"finding":"IRSp53 is required for Cdc42-dependent formation of basal filopodia that physically tether presumptive lens and retina to coordinate epithelial invagination during mouse eye development.","method":"IRSp53 (Baiap2) conditional KO mice, confocal and electron microscopy, filopodia quantification","journal":"Development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with specific morphogenetic phenotype in vivo, single lab","pmids":["19820184"],"is_preprint":false},{"year":2009,"finding":"SPIN90 directly associates with the SH3 domain of IRSp53 via its proline-rich domain; the SPIN90–IRSp53 complex forms at the leading edge and cooperatively mediates Rac activation and membrane ruffle formation.","method":"Co-IP, direct binding assay, siRNA knockdown, competitive inhibition, PDGF stimulation assay","journal":"Experimental Cell Research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct binding confirmed, siRNA knockdown with functional phenotype, single lab","pmids":["19460367"],"is_preprint":false},{"year":2010,"finding":"Tiam1 interacts with both IRSp53 and spinophilin to generate spatially localized Rac activation; IRSp53-dependent Rac activation mediates cell ruffling, spreading, and adhesion, whereas spinophilin-dependent Rac activation mediates cell migration.","method":"FRET-based Rac activity assay, RNAi knockdown, cell adhesion/spreading assays, signaling measurements","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET-based localized Rac activity measurement plus RNAi, single lab","pmids":["20360004"],"is_preprint":false},{"year":2011,"finding":"mDia1 and WAVE2 directly interact with IRSp53 within filopodia (confirmed by acceptor-photobleaching FRET); mDia1 and WAVE2 synergize specifically with IRSp53 (not mDia2 or WAVE1) to promote filopodia formation in neuronal cells.","method":"FRET (acceptor photobleaching), RNAi knockdown, time-lapse imaging of filopodia formation","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — FRET confirmation of direct interaction within filopodia plus selective RNAi knockdown with time-lapse phenotyping, single lab","pmids":["22179776"],"is_preprint":false},{"year":2011,"finding":"The crystal structure of the IRSp53 I-BAR domain in complex with a Tir-derived NPY peptide shows the homodimeric I-BAR binding two parallel Tir molecules; the NPY motif is specifically recognized by a conserved binding site on the I-BAR surface, confirmed by mutagenesis and in vivo binding assays.","method":"X-ray crystallography, site-directed mutagenesis, in vivo binding assay","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with mutagenesis validation and in vivo binding confirmation, single lab","pmids":["21893288"],"is_preprint":false},{"year":2011,"finding":"IRSp53 depletion reduces Rac1-dependent surface ruffling and CSF-1-induced actin polymerization and cell migration in macrophages; IRSp53 forms an immunoprecipitable complex with WAVE2 and Abi1 in a Rac1-activation-dependent manner, and IRSp53 is required for Rac1 association with WAVE2/Abi1.","method":"RNAi knockdown, Co-IP, Rac1Q61L expression, phagocytosis/protrusion assays","journal":"Journal of Cell Science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — RNAi plus Rac-dependency Co-IP in macrophages with multiple functional readouts, single lab","pmids":["18198193"],"is_preprint":false},{"year":2012,"finding":"LIN7 binding to the C-terminal PDZ-binding motif of IRSp53 is required for formation of actin-filled filopodia and neurites in neuronal cells; LIN7 silencing prevents IRSp53 incorporation into Triton X-100-insoluble (membrane-associated) complexes in differentiated cells.","method":"LIN7 siRNA knockdown, chimeric protein expression, live-cell imaging, Triton X-100 fractionation, neurite outgrowth assay","journal":"Journal of Cell Science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and chimeric rescue experiments plus biochemical fractionation, single lab","pmids":["22767515"],"is_preprint":false},{"year":2013,"finding":"CDC42 switches IRSp53 from inhibiting actin filament barbed-end growth to promoting VASP clustering; IRSp53 inhibits barbed-end growth, which is relieved by CDC42; IRSp53-dependent VASP clustering drives processive actin elongation for filopodia initiation; IRSp53 null mice display defective wound healing.","method":"In vitro actin polymerization assays, TIRF microscopy, liposome binding, IRSp53 KO mice wound healing assay, filopodia dynamics imaging","journal":"The EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with single-molecule TIRF plus multiple KO phenotypes, mechanistic dissection of VASP clustering","pmids":["24076653"],"is_preprint":false},{"year":2013,"finding":"IRSp53 knockdown attenuates podosome formation and migration in Src-transformed cells; IRSp53 physically interacts with VASP and links small GTPases to VASP for podosome formation; C-terminal splicing isoforms of IRSp53 do not affect this function.","method":"RNAi knockdown, Co-IP, podosome formation assay, cell migration assay, deletion mutant expression","journal":"PLoS One","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus RNAi with specific podosome phenotype, single lab","pmids":["23555988"],"is_preprint":false},{"year":2014,"finding":"Dynamin1 is an IRSp53-interacting partner that localizes to filopodia tips during initiation and assembly; dynamin GTPase activity and its actin-binding domain are required for filopodia formation, placing Dyn1 downstream of IRSp53 in a Dyn1–Mena–Eps8 regulatory network.","method":"Pulldown, FRET, RNAi knockdown, pharmacological inhibition (dynasore), TIRF live-cell imaging, expression of GTPase mutants","journal":"The Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET confirmation of interaction plus multiple genetic/pharmacological perturbations with live-cell dynamics, single lab","pmids":["25031323"],"is_preprint":false},{"year":2015,"finding":"IRSp53 knockout mice display enhanced NMDA receptor function in the hippocampus; treatment with the NMDAR antagonist memantine or the mGluR5 antagonist MPEP normalizes social interaction and NMDAR function/plasticity, establishing a causal link between elevated NMDAR activity and social deficits caused by IRSp53 loss.","method":"IRSp53 KO mice, behavioral testing, electrophysiology, pharmacological rescue with memantine/MPEP","journal":"Nature Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO plus pharmacological rescue with electrophysiological and behavioral correlates, replicated across multiple labs","pmids":["25622145"],"is_preprint":false},{"year":2015,"finding":"IRSp53 senses negative membrane curvature via its I-BAR domain; I-BAR dimers display non-monotonic curvature sorting, constricting weakly curved tubes at low tension while expanding them at high tension; at low protein density and tension, protein-rich domains form along membrane tubes.","method":"Protein encapsulation in giant unilamellar vesicles connected to membrane nanotubes, theoretical modeling","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — original biophysical reconstitution assay with quantitative theory, demonstrates curvature sensing mechanistically","pmids":["26469246"],"is_preprint":false},{"year":2015,"finding":"IRSp53 is involved in the Rac1–IRSp53–WAVE2–Arp2/3 signaling pathway; siRNA knockdown of IRSp53 decreases HIV-1 Gag membrane localization and viral particle release in CD4 T cells.","method":"siRNA knockdown, immunofluorescence confocal microscopy, membrane flotation assay, immunoblot","journal":"Journal of Virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi with multiple orthogonal readouts (membrane fractionation, immunofluorescence, particle production), single lab","pmids":["26018170"],"is_preprint":false},{"year":2019,"finding":"14-3-3 binds to two pairs of phosphorylation sites in IRSp53; each IRSp53 subunit independently binds one 14-3-3 dimer; 14-3-3 binding causes conformational changes (opposite to activatory Cdc42/Eps8 inputs) and inhibits IRSp53 binding to membranes and to Cdc42/downstream effectors.","method":"Phosphoproteomics, quantitative binding assays, crystallography of 14-3-3:phosphopeptide complexes, FRET-sensor assay with bicistronic heterodimer expression","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus FRET conformational sensor plus quantitative binding with mutagenesis, multiple orthogonal methods in one study","pmids":["30696821"],"is_preprint":false},{"year":2019,"finding":"AMPK phosphorylates two of the three 14-3-3 binding sites in IRSp53; pharmacological AMPK activation increases IRSp53 phosphorylation and 14-3-3 binding, inhibiting filopodia dynamics and cancer cell chemotaxis; mutating these sites reverses 14-3-3 inhibition.","method":"Pharmacological AMPK activation/inhibition, phosphorylation site mutagenesis, live-cell filopodia dynamics imaging, cancer cell chemotaxis assay","journal":"Molecular Biology of the Cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological and mutational evidence for AMPK as the kinase, functional filopodia and migration readouts, single lab","pmids":["30893014"],"is_preprint":false},{"year":2020,"finding":"IRSp53 controls lumen formation and positioning of polarity determinants (aPKC, podocalyxin) by regulating RAB35 localization/activity and by interacting with EPS8; IRSp53 genetic removal causes abnormal renal tubulogenesis with altered tubular polarity.","method":"IRSp53 KO mouse model, correlative light and electron microscopy (CLEM), Co-IP, RAB35 activity assay","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO in vivo plus CLEM plus RAB35 functional interaction, multiple orthogonal methods","pmids":["32665580"],"is_preprint":false},{"year":2021,"finding":"IRSp53 I-BAR domain is required for progression of HIV-1 membrane curvature during particle assembly; siRNA knockdown of IRSp53 arrests viral bud at half completion; IRSp53 is found in purified HIV-1 particles and is enriched around Gag assembly sites; HIV-1 Gag localizes preferentially to I-BAR-induced membrane curvature on GUVs.","method":"siRNA knockdown, single-molecule localization microscopy, GUV curvature assay, purification of HIV-1 particles with mass spectrometry","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (super-resolution microscopy, GUV reconstitution, purified virion proteomics) plus RNAi loss-of-function with specific structural phenotype","pmids":["34114563"],"is_preprint":false},{"year":2022,"finding":"Full-length IRSp53 self-assembles into clusters on membranes in a PIP2-dependent manner; IRSp53 clusters recruit VASP to locally assemble actin filaments and generate actin-filled membrane protrusions resembling filopodia in vitro; IRSp53 is enriched and triggers actin assembly only at highly dynamic membrane regions in live cells.","method":"In vitro reconstitution with GUVs and supported bilayers, live-cell membrane nanotube pulling, TIRF microscopy, molecular dynamics simulation","journal":"Science Advances","confidence":"High","confidence_rationale":"Tier 1 / Strong — full in vitro reconstitution of filopodium-like protrusions with defined components plus live-cell validation and MD simulation, multiple orthogonal methods","pmids":["36240267"],"is_preprint":false},{"year":2022,"finding":"Multivalent interactions between IRSp53 and PSD-95 or Shank3 drive liquid-liquid phase separation; IRSp53 is enriched in reconstituted excitatory PSD condensates via bridging to core and deeper PSD layers; PSD condensates promote bundled actin filament formation on membranes via IRSp53-mediated actin binding and bundling; disruption of IRSp53–actin interaction causes synaptic maturation defects in cortical neurons.","method":"Phase separation assay (in vitro droplet formation), PSD reconstitution, actin bundling assay on membranes, mutant overexpression in mouse cortical neurons","journal":"The Journal of Cell Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of phase separation and actin bundling with defined components plus neuronal functional validation, single lab multi-method study","pmids":["35819332"],"is_preprint":false},{"year":2023,"finding":"Eps8 forms heightened interactions with IRSp53 upon Arp2/3 inhibition, and the Eps8–IRSp53 complex drives linear actin polymerization required for tunnelling nanotube (TNT) formation over long distances.","method":"Micropatterning, optical tweezers, proteomics (Eps8 interactome upon Arp2/3 inhibition), RNAi knockdown, time-lapse microscopy","journal":"The EMBO Journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomic interaction shift plus optical tweezers functional assay, single lab","pmids":["38009333"],"is_preprint":false},{"year":2023,"finding":"IRSp53 mediates coupling of actin filaments to the plasma membrane at protrusive tips during cell migration on 1D fibers; IRSp53 depletion reduces actin stress fibers originating from cell periphery and uncouples nuclear movement from cell motility; IRSp53 controls retrograde actin flow at cell edges.","method":"RNAi knockdown, speckle microscopy for retrograde actin flow, live-cell migration assay on suspended 1D nanofibers, theoretical modeling","journal":"Advanced Science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi with quantitative actin flow measurements and migration assay in defined 1D geometry, single lab","pmids":["36698307"],"is_preprint":false},{"year":2024,"finding":"A de novo BAIAP2 variant p.Arg29Trp (in the I-BAR domain) causes a loss-of-function defect by preventing IRSp53 membrane localization; in utero electroporation of Baiap2 knockdown or expression of the variant causes abnormal neuronal migration, morphogenesis, and differentiation in the developing mouse cortex.","method":"In utero electroporation (knockdown and variant rescue), spatial transcriptomics, membrane localization assay","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function and variant rescue in vivo in developing brain plus mechanistic identification of membrane localization defect","pmids":["38149472"],"is_preprint":false},{"year":2024,"finding":"BIN1-mediated filopodia formation requires IRSp53; BIN1 colocalizes with F-actin along filopodia and bundles actin in vitro; BIN1 recruits actin-binding proteins (dynamin, ezrin) to negatively-curved membrane topologies in an IRSp53-dependent manner.","method":"RNAi knockdown, in vitro actin bundling assay, Co-IP, immunofluorescence colocalization","journal":"Communications Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro actin bundling plus RNAi dependency assay, single lab","pmids":["38724689"],"is_preprint":false},{"year":2019,"finding":"Robo2 binds directly to BAIAP2/IRSp53 through the I-BAR/IMD domain in renal epithelial cells; the Robo2–BAIAP2 complex allows Robo2 to phosphorylate MDM2 at Ser166 via BAIAP2, maintaining p53 homeostasis; disruption of this complex leads to MDM2 dephosphorylation, p53 accumulation, cellular senescence and cystic kidney disease.","method":"Co-IP, double KO mouse model, phosphorylation assay, rescue experiments","journal":"JCI Insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus genetic double-KO rescue plus phosphorylation assay, single lab","pmids":["31534052"],"is_preprint":false}],"current_model":"IRSp53/BAIAP2 is a multidomain I-BAR scaffolding protein that senses and generates negative membrane curvature (outward protrusions) via its PIP2-binding I-BAR domain, recruits actin regulatory proteins (WAVE2, Mena/VASP, Eps8, N-WASP, mDia1) through its SH3 domain downstream of Rac and Cdc42 GTPases, and bridges membrane deformation with actin polymerization to initiate filopodia and lamellipodia; at excitatory synapses it is incorporated into PSD condensates via Shank and PSD-95 interactions to limit NMDA receptor density and synaptic plasticity, while its activity is tuned by phosphorylation-dependent 14-3-3 binding (inhibitory), Par1b-mediated phosphorylation, and competition among SH3-domain partners."},"narrative":{"mechanistic_narrative":"BAIAP2 (IRSp53) is a multidomain scaffold that couples plasma-membrane deformation to actin polymerization, acting as the central node linking Rho-family GTPase signaling to the formation of filopodia, lamellipodia, and other membrane protrusions [PMID:11130076, PMID:11696321, PMID:17371834]. Its N-terminal I-BAR (IMD) domain binds PI(4,5)P2-rich membranes and deforms them into outward (negative-curvature) protrusions opposite to classical BAR domains, and this membrane-deforming activity—rather than actin bundling per se—is the critical determinant of filopodium induction [PMID:17371834, PMID:17003044]; biophysical reconstitution shows the I-BAR dimer senses negative membrane curvature in a tension-dependent manner [PMID:26469246]. The C-terminal SH3 domain recruits a competing repertoire of actin regulators—WAVE2, Mena/VASP, Eps8, N-WASP, mDia1, and SPIN90—downstream of activated Rac and Cdc42, with GTPase binding relieving an intramolecular autoinhibition to license SH3 engagement [PMID:11130076, PMID:11696321, PMID:15289329, PMID:18448434, PMID:22179776]. IRSp53 optimizes Rac/PIP3-dependent WAVE2–Arp2/3 activation on membranes [PMID:16702231] and, when clustered on PIP2 membranes, recruits VASP to drive processive actin elongation that builds filopodium-like protrusions in fully reconstituted systems [PMID:36240267, PMID:24076653]. Its activity is tuned by inhibitory phosphorylation-dependent 14-3-3 binding, which blocks membrane and Cdc42/effector engagement and is set by kinases including AMPK [PMID:30696821, PMID:19933840, PMID:30893014]. At excitatory synapses, IRSp53 is incorporated into PSD condensates through multivalent interactions with Shank and PSD-95 and limits NMDA receptor density and synaptic plasticity; its loss in mice enhances NMDAR-mediated transmission and produces social deficits reversible by NMDAR/mGluR5 antagonism [PMID:19208628, PMID:35819332, PMID:19193906, PMID:25622145]. The protein also serves morphogenetic roles in epithelial lumen formation and cortical neuronal migration, and is exploited by pathogens—bridging EHEC Tir/EspFU to actin pedestals and shaping HIV-1 membrane curvature during budding [PMID:32665580, PMID:38149472, PMID:19286134, PMID:34114563]. A de novo I-BAR domain variant (p.Arg29Trp) that abolishes membrane localization causes neurodevelopmental defects, establishing a direct link between IRSp53 membrane targeting and cortical development [PMID:38149472].","teleology":[{"year":2000,"claim":"Established IRSp53 as the physical bridge connecting active Rac to the WAVE actin nucleation machinery, defining its core role as a GTPase-to-actin adaptor.","evidence":"Co-IP and domain-binding assays reconstituting a Rac–IRSp53–WAVE trimolecular complex driving membrane ruffling","pmids":["11130076"],"confidence":"High","gaps":["Did not resolve how membrane binding integrates with this complex","Structural basis of the Rac-binding region not defined"]},{"year":2001,"claim":"Showed that Cdc42 binding relieves an intramolecular autoinhibition to license SH3-mediated effector recruitment, explaining GTPase-dependent switching toward filopodia.","evidence":"Affinity chromatography, Co-IP, dominant-negative expression and filopodia assays in fibroblasts identifying the IRSp53–Mena complex","pmids":["11696321"],"confidence":"High","gaps":["Atomic mechanism of autoinhibition relief not defined","Quantitative competition among SH3 partners not addressed"]},{"year":2002,"claim":"Identified Shank/ProSAP as a postsynaptic SH3 partner of IRSp53, anchoring it to the PSD and revealing Cdc42-regulated synaptic localization.","evidence":"Yeast two-hybrid, Co-IP from rat brain membranes, and mutational mapping; cellular redistribution assays in HEK cells","pmids":["12421375","12504591"],"confidence":"High","gaps":["Functional consequence at synapses not yet measured","Did not establish PSD condensate context"]},{"year":2004,"claim":"Defined the IRSp53–Eps8 complex at the leading edge as a positive amplifier of Rac signaling, linking membrane protrusion to GEF activation.","evidence":"Co-IP, direct binding, FRET in live cells, and invasion/motility assays","pmids":["15289329"],"confidence":"High","gaps":["Did not resolve competition with other SH3 partners","In vivo relevance of leading-edge complex untested"]},{"year":2005,"claim":"Crystal structure of the I-BAR (IMD) domain revealed a zeppelin-shaped coiled-coil dimer and tied basic-tip residues to actin bundling and filopodia induction.","evidence":"X-ray crystallography, analytical ultracentrifugation, in vitro actin bundling, and filopodia assays with mutagenesis","pmids":["15635447"],"confidence":"High","gaps":["Membrane-deformation role of the domain not yet separated from actin bundling","Relative contribution of bundling vs curvature unresolved at this stage"]},{"year":2007,"claim":"Resolved the central mechanism by showing the I-BAR domain binds PI(4,5)P2 and generates outward (negative) membrane curvature, the activity critical for filopodium induction—distinct from actin bundling.","evidence":"In vitro PI(4,5)P2 liposome tubulation, electron microscopy, mutagenesis separating activities, and cellular filopodia assays","pmids":["17371834","17003044"],"confidence":"High","gaps":["How membrane curvature is coupled in time to actin assembly not yet reconstituted","Tension dependence of curvature activity not addressed"]},{"year":2008,"claim":"Demonstrated that the I-BAR domain alone makes actin-free protrusions while SH3 partners (N-WASP, Mena/VASP) are required for full filopodia, partitioning the membrane-shaping and actin-elongating functions.","evidence":"Co-IP and reconstitution in N-WASP and Mena/VASP knockout fibroblasts with domain mutants","pmids":["18448434"],"confidence":"High","gaps":["Did not identify which elongation mechanism dominates in vivo","Regulation of partner selection unresolved"]},{"year":2009,"claim":"Genetic knockout established IRSp53 as a negative regulator of NMDA receptor function and synaptic plasticity, embedding it in postsynaptic Shank/Eps8 competition that controls PSD composition.","evidence":"IRSp53 KO mice with electrophysiology (AMPA/NMDA ratio, LTP), immuno-EM of PSD, and competitive binding assays","pmids":["19193906","19208628"],"confidence":"High","gaps":["Molecular basis of NMDAR restriction not fully defined","Link to behavior not yet established at this stage"]},{"year":2009,"claim":"Revealed multiple negative regulators (14-3-3, Kank, synaptopodin) that selectively gate IRSp53 toward Rac- or Cdc42-driven protrusions, establishing combinatorial control of its output.","evidence":"Phospho-site mapping, Co-IP competition, RNAi, and live-cell filopodia/lamellipodia assays","pmids":["19933840","19171758","17569780"],"confidence":"High","gaps":["Kinases setting 14-3-3 sites not yet identified","Structural basis of 14-3-3 inhibition unresolved"]},{"year":2009,"claim":"Showed IRSp53 is the host factor coupling EHEC Tir to EspFU and N-WASP for actin pedestal assembly, extending its adaptor role to pathogen-driven actin polymerization.","evidence":"Co-IP, direct binding, IRSp53 KO cells, and immunofluorescence colocalization in actin pedestals","pmids":["19286134"],"confidence":"High","gaps":["Structural recognition of the Tir NPY motif not yet defined (resolved later)","Generality to other I-BAR proteins untested here"]},{"year":2011,"claim":"Crystallography of the I-BAR–Tir NPY peptide complex defined a conserved surface binding site, providing structural detail for pathogen hijacking of IRSp53.","evidence":"X-ray crystallography with mutagenesis and in vivo binding validation","pmids":["21893288"],"confidence":"High","gaps":["Whether host ligands use the same I-BAR surface not addressed"]},{"year":2013,"claim":"Reconstitution revealed the GTPase switch at the actin barbed end: IRSp53 inhibits barbed-end growth until CDC42 relieves it and converts IRSp53 into a VASP-clustering factor driving processive elongation, with in vivo wound-healing requirement.","evidence":"In vitro actin polymerization, single-molecule TIRF, liposome binding, and IRSp53 KO mouse wound-healing assays","pmids":["24076653"],"confidence":"High","gaps":["Stoichiometry of VASP clustering on membranes not defined here","How phosphoregulation intersects this switch not addressed"]},{"year":2015,"claim":"Quantified the biophysics of I-BAR curvature sensing, showing tension-dependent, non-monotonic sorting and density-dependent domain formation on membrane tubes.","evidence":"Protein encapsulation in GUVs connected to membrane nanotubes with theoretical modeling","pmids":["26469246"],"confidence":"High","gaps":["Coupling of sensing to actin assembly not reconstituted in this system","Full-length protein behavior not yet tested here"]},{"year":2015,"claim":"Linked elevated NMDAR activity to behavioral deficits by showing NMDAR/mGluR5 antagonists rescue social impairments in IRSp53 KO mice, establishing causal relevance to circuit function.","evidence":"IRSp53 KO mice with behavioral testing, electrophysiology, and pharmacological rescue (memantine/MPEP)","pmids":["25622145"],"confidence":"High","gaps":["Molecular mechanism limiting NMDAR density not fully defined","Cell-type specificity of the deficit unresolved"]},{"year":2019,"claim":"Defined the structural and conformational basis of 14-3-3 inhibition and identified AMPK as a kinase setting these sites, providing a metabolic input that suppresses filopodia and chemotaxis.","evidence":"Phosphoproteomics, crystallography of 14-3-3:phosphopeptide complexes, FRET conformational sensors, and pharmacological AMPK modulation with site mutants","pmids":["30696821","30893014"],"confidence":"High","gaps":["Full set of physiological kinases at these sites not enumerated","Dynamics of 14-3-3 release in cells not measured"]},{"year":2020,"claim":"Extended IRSp53 function to epithelial morphogenesis, showing it controls lumen formation and apical polarity via RAB35 and EPS8 in renal tubulogenesis.","evidence":"IRSp53 KO mouse, CLEM, Co-IP, and RAB35 activity assays","pmids":["32665580"],"confidence":"High","gaps":["Mechanism linking membrane curvature to RAB35 regulation unresolved","Whether actin assembly is required not fully separated"]},{"year":2021,"claim":"Demonstrated that the I-BAR domain shapes HIV-1 membrane curvature during budding, with Gag enriching at I-BAR-induced curvature, identifying a viral exploitation of IRSp53 curvature activity.","evidence":"siRNA knockdown, single-molecule localization microscopy, GUV curvature assays, and proteomics of purified virions","pmids":["34114563"],"confidence":"High","gaps":["Direct Gag–IRSp53 contact not defined","Whether actin machinery contributes to budding unresolved"]},{"year":2022,"claim":"Achieved full reconstitution of IRSp53-driven filopodium-like protrusions, showing PIP2-dependent self-clustering recruits VASP for local actin assembly at dynamic membrane regions.","evidence":"In vitro reconstitution on GUVs and supported bilayers, membrane nanotube pulling, TIRF, live-cell imaging, and MD simulation","pmids":["36240267"],"confidence":"High","gaps":["Regulatory inputs not included in minimal system","Quantitative threshold for clustering in cells not defined"]},{"year":2022,"claim":"Showed IRSp53 partitions into PSD liquid-liquid phase-separated condensates via PSD-95/Shank3 bridging and links these condensates to membrane-associated actin bundling required for synapse maturation.","evidence":"In vitro droplet/PSD reconstitution, actin bundling assays on membranes, and mutant expression in mouse cortical neurons","pmids":["35819332"],"confidence":"High","gaps":["How condensate incorporation tunes NMDAR density mechanistically not resolved","In vivo relevance of phase separation untested"]},{"year":2024,"claim":"Connected IRSp53 to neurodevelopmental disease by showing a de novo I-BAR variant (p.Arg29Trp) abolishes membrane localization and disrupts cortical neuronal migration and morphogenesis.","evidence":"In utero electroporation knockdown and variant rescue, spatial transcriptomics, and membrane localization assays in developing mouse cortex","pmids":["38149472"],"confidence":"High","gaps":["Human clinical spectrum not defined from this study","Downstream actin pathway altered by the variant not mapped"]},{"year":null,"claim":"How the competing inputs (GTPases, phosphorylation/14-3-3, SH3 partner competition, membrane tension, and phase separation) are integrated to determine when and where IRSp53 builds a specific protrusion type in vivo remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No unified model coupling membrane tension, GTPase state, and phosphoregulation in living cells","Quantitative rules for SH3-partner selection in different cell types unknown","Mechanism by which IRSp53 restricts synaptic NMDAR density not molecularly defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,7,15,17,30]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[13,12,35,41]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[8,11,31,42]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[8,13,35,41]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[10,21,22,37]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,6,13,41]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6,8,31,44]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[23,42]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,10,26]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[20,23,34,42]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[24,39,45]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[19,36,40,47]}],"complexes":["Rac–IRSp53–WAVE2 complex","IRSp53–Eps8 complex","WAVE2/Abi1–IRSp53 complex","PSD (PSD-95/Shank) condensate"],"partners":["WASF2","EPS8","ENAH","SHANK1","DLG4","DIAPH1","WASL","BAI1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UQB8","full_name":"BAR/IMD domain-containing adapter protein 2","aliases":["Brain-specific angiogenesis inhibitor 1-associated protein 2","BAI-associated protein 2","BAI1-associated protein 2","Protein BAP2","Fas ligand-associated factor 3","FLAF3","Insulin receptor substrate p53/p58","IRS-58","IRSp53/58","Insulin receptor substrate protein of 53 kDa","IRSp53","Insulin receptor substrate p53"],"length_aa":552,"mass_kda":60.9,"function":"Adapter protein that links membrane-bound small G-proteins to cytoplasmic effector proteins. Necessary for CDC42-mediated reorganization of the actin cytoskeleton and for RAC1-mediated membrane ruffling. Involved in the regulation of the actin cytoskeleton by WASF family members and the Arp2/3 complex. Plays a role in neurite growth. Acts syngeristically with ENAH to promote filipodia formation. Plays a role in the reorganization of the actin cytoskeleton in response to bacterial infection. Participates in actin bundling when associated with EPS8, promoting filopodial protrusions","subcellular_location":"Cytoplasm; Membrane; Cell projection, filopodium; Cell projection, ruffle; Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/Q9UQB8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BAIAP2","classification":"Not Classified","n_dependent_lines":8,"n_total_lines":1208,"dependency_fraction":0.006622516556291391},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000175866","cell_line_id":"CID000665","localizations":[{"compartment":"cell_contact","grade":3},{"compartment":"membrane","grade":3},{"compartment":"cytoplasmic","grade":2}],"interactors":[{"gene":"CAMK2G","stoichiometry":10.0},{"gene":"ACTG1","stoichiometry":4.0},{"gene":"NCKAP1","stoichiometry":4.0},{"gene":"ACTB","stoichiometry":0.2},{"gene":"ACTR2","stoichiometry":0.2},{"gene":"ARL3","stoichiometry":0.2},{"gene":"ARL6IP6","stoichiometry":0.2},{"gene":"ARL8A","stoichiometry":0.2},{"gene":"ARL8B","stoichiometry":0.2},{"gene":"CYFIP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000665","total_profiled":1310},"omim":[{"mim_id":"621468","title":"DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY 120; DEE120","url":"https://www.omim.org/entry/621468"},{"mim_id":"616951","title":"MTSS I-BAR DOMAIN-CONTAINING PROTEIN 2; MTSS2","url":"https://www.omim.org/entry/616951"},{"mim_id":"611877","title":"BAI1-ASSOCIATED PROTEIN 2-LIKE 1; BAIAP2L1","url":"https://www.omim.org/entry/611877"},{"mim_id":"608486","title":"MTTS I-BAR DOMAIN-CONTAINING PROTEIN 1; MTSS1","url":"https://www.omim.org/entry/608486"},{"mim_id":"607151","title":"MOYAMOYA DISEASE 2; MYMY2","url":"https://www.omim.org/entry/607151"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Plasma membrane","reliability":"Enhanced"},{"location":"Cytosol","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/BAIAP2"},"hgnc":{"alias_symbol":["BAP2","IRSp53","WAML"],"prev_symbol":[]},"alphafold":{"accession":"Q9UQB8","domains":[{"cath_id":"1.20.1270.60","chopping":"2-231","consensus_level":"high","plddt":96.222,"start":2,"end":231},{"cath_id":"2.30.30.40","chopping":"379-436","consensus_level":"high","plddt":93.3472,"start":379,"end":436}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UQB8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UQB8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UQB8-F1-predicted_aligned_error_v6.png","plddt_mean":71.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BAIAP2","jax_strain_url":"https://www.jax.org/strain/search?query=BAIAP2"},"sequence":{"accession":"Q9UQB8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UQB8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UQB8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UQB8"}},"corpus_meta":[{"pmid":"11130076","id":"PMC_11130076","title":"IRSp53 is an essential intermediate between Rac and WAVE in the regulation of membrane ruffling.","date":"2000","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/11130076","citation_count":454,"is_preprint":false},{"pmid":"11696321","id":"PMC_11696321","title":"Cdc42 induces filopodia by promoting the formation of an IRSp53:Mena complex.","date":"2001","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/11696321","citation_count":326,"is_preprint":false},{"pmid":"17371834","id":"PMC_17371834","title":"Missing-in-metastasis and IRSp53 deform PI(4,5)P2-rich membranes by an inverse BAR domain-like mechanism.","date":"2007","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17371834","citation_count":310,"is_preprint":false},{"pmid":"17115031","id":"PMC_17115031","title":"Regulation of cell shape by Cdc42 is mediated by the synergic actin-bundling activity of the Eps8-IRSp53 complex.","date":"2006","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17115031","citation_count":206,"is_preprint":false},{"pmid":"18215522","id":"PMC_18215522","title":"IRSp53: crossing the road of membrane and actin dynamics in the formation of membrane protrusions.","date":"2008","source":"Trends in cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/18215522","citation_count":203,"is_preprint":false},{"pmid":"15635447","id":"PMC_15635447","title":"Structural basis of filopodia formation induced by the IRSp53/MIM homology domain of human IRSp53.","date":"2005","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/15635447","citation_count":198,"is_preprint":false},{"pmid":"26469246","id":"PMC_26469246","title":"IRSp53 senses negative membrane curvature and phase separates along membrane tubules.","date":"2015","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/26469246","citation_count":170,"is_preprint":false},{"pmid":"17003044","id":"PMC_17003044","title":"The RAC binding domain/IRSp53-MIM homology domain of IRSp53 induces RAC-dependent membrane deformation.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17003044","citation_count":146,"is_preprint":false},{"pmid":"17569780","id":"PMC_17569780","title":"Synaptopodin protects against proteinuria by disrupting Cdc42:IRSp53:Mena signaling complexes in kidney podocytes.","date":"2007","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/17569780","citation_count":142,"is_preprint":false},{"pmid":"25622145","id":"PMC_25622145","title":"Social deficits in IRSp53 mutant mice improved by NMDAR and mGluR5 suppression.","date":"2015","source":"Nature neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/25622145","citation_count":141,"is_preprint":false},{"pmid":"16702231","id":"PMC_16702231","title":"Optimization of WAVE2 complex-induced actin polymerization by membrane-bound IRSp53, PIP(3), and Rac.","date":"2006","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/16702231","citation_count":136,"is_preprint":false},{"pmid":"19193906","id":"PMC_19193906","title":"Enhanced NMDA receptor-mediated synaptic transmission, enhanced long-term potentiation, and impaired learning and memory in mice lacking IRSp53.","date":"2009","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/19193906","citation_count":128,"is_preprint":false},{"pmid":"30778383","id":"PMC_30778383","title":"Nanoplasmonic Sensor Detects Preferential Binding of IRSp53 to Negative Membrane Curvature.","date":"2019","source":"Frontiers in chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30778383","citation_count":127,"is_preprint":false},{"pmid":"18448434","id":"PMC_18448434","title":"The Cdc42 effector IRSp53 generates filopodia by coupling membrane protrusion with actin dynamics.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18448434","citation_count":126,"is_preprint":false},{"pmid":"19913105","id":"PMC_19913105","title":"I-BAR domains, IRSp53 and filopodium formation.","date":"2009","source":"Seminars in cell & developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/19913105","citation_count":121,"is_preprint":false},{"pmid":"12734400","id":"PMC_12734400","title":"IRSp53 is colocalised with WAVE2 at the tips of protruding lamellipodia and filopodia independently of Mena.","date":"2003","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/12734400","citation_count":113,"is_preprint":false},{"pmid":"15289329","id":"PMC_15289329","title":"IRSp53/Eps8 complex is important for positive regulation of Rac and cancer cell motility/invasiveness.","date":"2004","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/15289329","citation_count":106,"is_preprint":false},{"pmid":"12421375","id":"PMC_12421375","title":"ProSAP/Shank postsynaptic density proteins interact with insulin receptor tyrosine kinase substrate IRSp53.","date":"2002","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12421375","citation_count":100,"is_preprint":false},{"pmid":"24076653","id":"PMC_24076653","title":"CDC42 switches IRSp53 from inhibition of actin growth to elongation by clustering of VASP.","date":"2013","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/24076653","citation_count":99,"is_preprint":false},{"pmid":"7495881","id":"PMC_7495881","title":"BAP2, a gene encoding a permease for branched-chain amino acids in Saccharomyces cerevisiae.","date":"1995","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/7495881","citation_count":96,"is_preprint":false},{"pmid":"19286134","id":"PMC_19286134","title":"IRSp53 links the enterohemorrhagic E. coli effectors Tir and EspFU for actin pedestal formation.","date":"2009","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/19286134","citation_count":89,"is_preprint":false},{"pmid":"15899863","id":"PMC_15899863","title":"Tiam1-IRSp53 complex formation directs specificity of rac-mediated actin cytoskeleton regulation.","date":"2005","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15899863","citation_count":85,"is_preprint":false},{"pmid":"19820184","id":"PMC_19820184","title":"Cdc42- and IRSp53-dependent contractile filopodia tether presumptive lens and retina to coordinate epithelial invagination.","date":"2009","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/19820184","citation_count":81,"is_preprint":false},{"pmid":"22179776","id":"PMC_22179776","title":"mDia1 and WAVE2 proteins interact directly with IRSp53 in filopodia and are involved in filopodium formation.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22179776","citation_count":77,"is_preprint":false},{"pmid":"12504591","id":"PMC_12504591","title":"The insulin receptor substrate IRSp53 links postsynaptic shank1 to the small G-protein cdc42.","date":"2002","source":"Molecular and cellular neurosciences","url":"https://pubmed.ncbi.nlm.nih.gov/12504591","citation_count":75,"is_preprint":false},{"pmid":"10814512","id":"PMC_10814512","title":"Rho small G-protein-dependent binding of mDia to an Src homology 3 domain-containing IRSp53/BAIAP2.","date":"2000","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10814512","citation_count":73,"is_preprint":false},{"pmid":"10343108","id":"PMC_10343108","title":"Identification of BAIAP2 (BAI-associated protein 2), a novel human homologue of hamster IRSp53, whose SH3 domain interacts with the cytoplasmic domain of BAI1.","date":"1999","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10343108","citation_count":72,"is_preprint":false},{"pmid":"17430976","id":"PMC_17430976","title":"Characterisation of IRTKS, a novel IRSp53/MIM family actin regulator with distinct filament bundling properties.","date":"2007","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/17430976","citation_count":71,"is_preprint":false},{"pmid":"19208628","id":"PMC_19208628","title":"The insulin receptor substrate of 53 kDa (IRSp53) limits hippocampal synaptic plasticity.","date":"2009","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19208628","citation_count":70,"is_preprint":false},{"pmid":"18198193","id":"PMC_18198193","title":"Membrane targeting of WAVE2 is not sufficient for WAVE2-dependent actin polymerization: a role for IRSp53 in mediating the interaction between Rac and WAVE2.","date":"2008","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18198193","citation_count":68,"is_preprint":false},{"pmid":"26275848","id":"PMC_26275848","title":"IRSp53/BAIAP2 in dendritic spine development, NMDA receptor regulation, and psychiatric disorders.","date":"2015","source":"Neuropharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/26275848","citation_count":64,"is_preprint":false},{"pmid":"8606179","id":"PMC_8606179","title":"Amino acids induce expression of BAP2, a branched-chain amino acid permease gene in Saccharomyces cerevisiae.","date":"1996","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/8606179","citation_count":64,"is_preprint":false},{"pmid":"22316129","id":"PMC_22316129","title":"Evolution of the eukaryotic ARP2/3 activators of the WASP family: WASP, WAVE, WASH, and WHAMM, and the proposed new family members WAWH and WAML.","date":"2012","source":"BMC research notes","url":"https://pubmed.ncbi.nlm.nih.gov/22316129","citation_count":53,"is_preprint":false},{"pmid":"19733838","id":"PMC_19733838","title":"Case-control study of six genes asymmetrically expressed in the two cerebral hemispheres: association of BAIAP2 with attention-deficit/hyperactivity disorder.","date":"2009","source":"Biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/19733838","citation_count":53,"is_preprint":false},{"pmid":"11212916","id":"PMC_11212916","title":"Transcriptional regulation of the Saccharomyces cerevisiae amino acid permease gene BAP2.","date":"2001","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/11212916","citation_count":50,"is_preprint":false},{"pmid":"19889090","id":"PMC_19889090","title":"Dissecting the role of the Tir:Nck and Tir:IRTKS/IRSp53 signalling pathways in vivo.","date":"2009","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/19889090","citation_count":50,"is_preprint":false},{"pmid":"21814501","id":"PMC_21814501","title":"The Eps8/IRSp53/VASP network differentially controls actin capping and bundling in filopodia formation.","date":"2011","source":"PLoS computational biology","url":"https://pubmed.ncbi.nlm.nih.gov/21814501","citation_count":49,"is_preprint":false},{"pmid":"21282462","id":"PMC_21282462","title":"The serine/threonine kinase Par1b regulates epithelial lumen polarity via IRSp53-mediated cell-ECM signaling.","date":"2011","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21282462","citation_count":46,"is_preprint":false},{"pmid":"19933840","id":"PMC_19933840","title":"Regulation of IRSp53-dependent filopodial dynamics by antagonism between 14-3-3 binding and SH3-mediated localization.","date":"2009","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19933840","citation_count":45,"is_preprint":false},{"pmid":"19171758","id":"PMC_19171758","title":"Kank attenuates actin remodeling by preventing interaction between IRSp53 and Rac1.","date":"2009","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/19171758","citation_count":44,"is_preprint":false},{"pmid":"30696821","id":"PMC_30696821","title":"Mechanism of IRSp53 inhibition by 14-3-3.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30696821","citation_count":40,"is_preprint":false},{"pmid":"36240267","id":"PMC_36240267","title":"Activated I-BAR IRSp53 clustering controls the formation of VASP-actin-based membrane protrusions.","date":"2022","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/36240267","citation_count":38,"is_preprint":false},{"pmid":"9065387","id":"PMC_9065387","title":"STP1, a gene involved in pre-tRNA processing in yeast, is important for amino-acid uptake and transcription of the permease gene BAP2.","date":"1997","source":"Current genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9065387","citation_count":37,"is_preprint":false},{"pmid":"26018170","id":"PMC_26018170","title":"Involvement of the Rac1-IRSp53-Wave2-Arp2/3 Signaling Pathway in HIV-1 Gag Particle Release in CD4 T Cells.","date":"2015","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/26018170","citation_count":35,"is_preprint":false},{"pmid":"38009333","id":"PMC_38009333","title":"Tunnelling nanotube formation is driven by Eps8/IRSp53-dependent linear actin polymerization.","date":"2023","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/38009333","citation_count":31,"is_preprint":false},{"pmid":"34114563","id":"PMC_34114563","title":"Full assembly of HIV-1 particles requires assistance of the membrane curvature factor IRSp53.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/34114563","citation_count":31,"is_preprint":false},{"pmid":"32665580","id":"PMC_32665580","title":"IRSp53 controls plasma membrane shape and polarized transport at the nascent lumen in epithelial tubules.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32665580","citation_count":30,"is_preprint":false},{"pmid":"19054385","id":"PMC_19054385","title":"LIN7 mediates the recruitment of IRSp53 to tight junctions.","date":"2008","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/19054385","citation_count":30,"is_preprint":false},{"pmid":"19083995","id":"PMC_19083995","title":"The postsynaptic density protein, IQ-ArfGEF/BRAG1, can interact with IRSp53 through its proline-rich sequence.","date":"2008","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/19083995","citation_count":28,"is_preprint":false},{"pmid":"24639075","id":"PMC_24639075","title":"Postsynaptic distribution of IRSp53 in spiny excitatory and inhibitory neurons.","date":"2014","source":"The Journal of comparative neurology","url":"https://pubmed.ncbi.nlm.nih.gov/24639075","citation_count":27,"is_preprint":false},{"pmid":"20418908","id":"PMC_20418908","title":"The interplay between Eps8 and IRSp53 contributes to Src-mediated transformation.","date":"2010","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/20418908","citation_count":26,"is_preprint":false},{"pmid":"14596909","id":"PMC_14596909","title":"MALS is a binding partner of IRSp53 at cell-cell contacts.","date":"2003","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/14596909","citation_count":26,"is_preprint":false},{"pmid":"11741283","id":"PMC_11741283","title":"Distinctive tissue distribution and phosphorylation of IRSp53 isoforms.","date":"2001","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11741283","citation_count":25,"is_preprint":false},{"pmid":"20360004","id":"PMC_20360004","title":"Scaffold proteins IRSp53 and spinophilin regulate localized Rac activation by T-lymphocyte invasion and metastasis protein 1 (TIAM1).","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20360004","citation_count":25,"is_preprint":false},{"pmid":"21893288","id":"PMC_21893288","title":"Structural basis for complex formation between human IRSp53 and the translocated intimin receptor Tir of enterohemorrhagic E. coli.","date":"2011","source":"Structure (London, England : 1993)","url":"https://pubmed.ncbi.nlm.nih.gov/21893288","citation_count":24,"is_preprint":false},{"pmid":"30893014","id":"PMC_30893014","title":"IRSp53 coordinates AMPK and 14-3-3 signaling to regulate filopodia dynamics and directed cell migration.","date":"2019","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/30893014","citation_count":22,"is_preprint":false},{"pmid":"25586189","id":"PMC_25586189","title":"SH2B1 and IRSp53 proteins promote the formation of dendrites and dendritic branches.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25586189","citation_count":22,"is_preprint":false},{"pmid":"25031323","id":"PMC_25031323","title":"Dynamin1 is a novel target for IRSp53 protein and works with mammalian enabled (Mena) protein and Eps8 to regulate filopodial dynamics.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25031323","citation_count":22,"is_preprint":false},{"pmid":"35819332","id":"PMC_35819332","title":"IRSp53 promotes postsynaptic density formation and actin filament bundling.","date":"2022","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/35819332","citation_count":21,"is_preprint":false},{"pmid":"22767515","id":"PMC_22767515","title":"LIN7 regulates the filopodium- and neurite-promoting activity of IRSp53.","date":"2012","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/22767515","citation_count":21,"is_preprint":false},{"pmid":"26560964","id":"PMC_26560964","title":"Severe learning deficits of IRSp53 mutant mice are caused by altered NMDA receptor-dependent signal transduction.","date":"2015","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26560964","citation_count":20,"is_preprint":false},{"pmid":"36698307","id":"PMC_36698307","title":"Actin Filaments Couple the Protrusive Tips to the Nucleus through the I-BAR Domain Protein IRSp53 during the Migration of Cells on 1D Fibers.","date":"2023","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/36698307","citation_count":19,"is_preprint":false},{"pmid":"14757244","id":"PMC_14757244","title":"The N-terminal domain of yeast Bap2 permease is phosphorylated dependently on the Npr1 kinase in response to starvation.","date":"2004","source":"FEMS microbiology letters","url":"https://pubmed.ncbi.nlm.nih.gov/14757244","citation_count":18,"is_preprint":false},{"pmid":"28067313","id":"PMC_28067313","title":"Redundant functions of I-BAR family members, IRSp53 and IRTKS, are essential for embryonic development.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28067313","citation_count":17,"is_preprint":false},{"pmid":"9153753","id":"PMC_9153753","title":"The branched-chain amino acid permease gene of Saccharomyces cerevisiae, BAP2, encodes the high-affinity leucine permease (S1).","date":"1997","source":"Yeast (Chichester, England)","url":"https://pubmed.ncbi.nlm.nih.gov/9153753","citation_count":17,"is_preprint":false},{"pmid":"32116566","id":"PMC_32116566","title":"IRSp53 Deletion in Glutamatergic and GABAergic Neurons and in Male and Female Mice Leads to Distinct Electrophysiological and Behavioral Phenotypes.","date":"2020","source":"Frontiers in cellular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/32116566","citation_count":16,"is_preprint":false},{"pmid":"35844059","id":"PMC_35844059","title":"Extracellular vesicles containing the I-BAR protein IRSp53 are released from the cell plasma membrane in an Arp2/3 dependent manner.","date":"2022","source":"Biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/35844059","citation_count":16,"is_preprint":false},{"pmid":"23750457","id":"PMC_23750457","title":"The type III TGFβ receptor regulates filopodia formation via a Cdc42-mediated IRSp53-N-WASP interaction in epithelial cells.","date":"2013","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/23750457","citation_count":16,"is_preprint":false},{"pmid":"23555988","id":"PMC_23555988","title":"IRSp53 mediates podosome formation via VASP in NIH-Src cells.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23555988","citation_count":15,"is_preprint":false},{"pmid":"22465711","id":"PMC_22465711","title":"Insulin receptor substrate protein 53kDa (IRSp53) is a negative regulator of myogenic differentiation.","date":"2012","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/22465711","citation_count":14,"is_preprint":false},{"pmid":"24392092","id":"PMC_24392092","title":"BAIAP2 is related to emotional modulation of human memory strength.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24392092","citation_count":14,"is_preprint":false},{"pmid":"34616498","id":"PMC_34616498","title":"E2F1-Induced lncRNA BAIAP2-AS1 Overexpression Contributes to the Malignant Progression of Hepatocellular Carcinoma via miR-361-3p/SOX4 Axis.","date":"2021","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/34616498","citation_count":13,"is_preprint":false},{"pmid":"28938222","id":"PMC_28938222","title":"Inter-hemispherical asymmetry in default-mode functional connectivity and BAIAP2 gene are associated with anger expression in ADHD adults.","date":"2017","source":"Psychiatry research. Neuroimaging","url":"https://pubmed.ncbi.nlm.nih.gov/28938222","citation_count":13,"is_preprint":false},{"pmid":"19460367","id":"PMC_19460367","title":"SPIN90-IRSp53 complex participates in Rac-induced membrane ruffling.","date":"2009","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/19460367","citation_count":12,"is_preprint":false},{"pmid":"20678498","id":"PMC_20678498","title":"The mammalian verprolin, WIRE induces filopodia independent of N-WASP through IRSp53.","date":"2010","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/20678498","citation_count":11,"is_preprint":false},{"pmid":"31711240","id":"PMC_31711240","title":"HDAC inhibition induces expression of scaffolding proteins critical for tumor progression in pediatric glioma: focus on EBP50 and IRSp53.","date":"2020","source":"Neuro-oncology","url":"https://pubmed.ncbi.nlm.nih.gov/31711240","citation_count":11,"is_preprint":false},{"pmid":"18417251","id":"PMC_18417251","title":"Identification of the insulin-responsive tyrosine phosphorylation sites on IRSp53.","date":"2008","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/18417251","citation_count":11,"is_preprint":false},{"pmid":"30792430","id":"PMC_30792430","title":"Superresolution microscopy reveals distinct localisation of full length IRSp53 and its I-BAR domain protein within filopodia.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30792430","citation_count":11,"is_preprint":false},{"pmid":"29284046","id":"PMC_29284046","title":"IRSp53 accumulates at the postsynaptic density under excitatory conditions.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/29284046","citation_count":10,"is_preprint":false},{"pmid":"35865874","id":"PMC_35865874","title":"Identification of TRAPPC9 and BAIAP2 Gene Polymorphisms and Their Association With Fat Deposition-Related Traits in Hu Sheep.","date":"2022","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/35865874","citation_count":10,"is_preprint":false},{"pmid":"37730842","id":"PMC_37730842","title":"The PFC-LH-VTA pathway contributes to social deficits in IRSp53-mutant mice.","date":"2023","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/37730842","citation_count":8,"is_preprint":false},{"pmid":"35982261","id":"PMC_35982261","title":"Adult re-expression of IRSp53 rescues NMDA receptor function and social behavior in IRSp53-mutant mice.","date":"2022","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/35982261","citation_count":7,"is_preprint":false},{"pmid":"38149472","id":"PMC_38149472","title":"A lissencephaly-associated BAIAP2 variant causes defects in neuronal migration during brain development.","date":"2024","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/38149472","citation_count":7,"is_preprint":false},{"pmid":"36317872","id":"PMC_36317872","title":"Suppressed prefrontal neuronal firing variability and impaired social representation in IRSp53-mutant mice.","date":"2022","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/36317872","citation_count":7,"is_preprint":false},{"pmid":"24416406","id":"PMC_24416406","title":"Ist2 in the yeast cortical endoplasmic reticulum promotes trafficking of the amino acid transporter Bap2 to the plasma membrane.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24416406","citation_count":7,"is_preprint":false},{"pmid":"25175559","id":"PMC_25175559","title":"SH2B1 increases the numbers of IRSp53-induced filopodia.","date":"2014","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/25175559","citation_count":6,"is_preprint":false},{"pmid":"38724689","id":"PMC_38724689","title":"BIN1 regulates actin-membrane interactions during IRSp53-dependent filopodia formation.","date":"2024","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/38724689","citation_count":6,"is_preprint":false},{"pmid":"37685917","id":"PMC_37685917","title":"Molecular Relay Stations in Membrane Nanotubes: IRSp53 Involved in Actin-Based Force Generation.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37685917","citation_count":6,"is_preprint":false},{"pmid":"20707603","id":"PMC_20707603","title":"The neuronal proteins CIPP, Cypin and IRSp53 form a tripartite complex mediated by PDZ and SH3 domains.","date":"2010","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20707603","citation_count":6,"is_preprint":false},{"pmid":"37234209","id":"PMC_37234209","title":"Hippocampal BAIAP2 prevents chronic mild stress-induced depression-like behaviors in mice.","date":"2023","source":"Frontiers in psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/37234209","citation_count":5,"is_preprint":false},{"pmid":"27320196","id":"PMC_27320196","title":"Novel localisation and possible function of LIN7 and IRSp53 in mitochondria of HeLa cells.","date":"2016","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/27320196","citation_count":5,"is_preprint":false},{"pmid":"21542353","id":"PMC_21542353","title":"[A molecular dynamics study of the interaction between domain I-BAR of the IRSp53 protein and negatively charged membranes].","date":"2011","source":"Biofizika","url":"https://pubmed.ncbi.nlm.nih.gov/21542353","citation_count":5,"is_preprint":false},{"pmid":"31534052","id":"PMC_31534052","title":"Disruption of Robo2-Baiap2 integrated signaling drives cystic disease.","date":"2019","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/31534052","citation_count":4,"is_preprint":false},{"pmid":"31531927","id":"PMC_31531927","title":"Proteomics Analysis Identifies IRSp53 and Fascin as Critical for PRV Egress and Direct Cell-Cell Transmission.","date":"2019","source":"Proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/31531927","citation_count":4,"is_preprint":false},{"pmid":"32535200","id":"PMC_32535200","title":"IRSp53 is a novel interactor of SHIP2: A role of the actin binding protein Mena in their cellular localization in breast cancer cells.","date":"2020","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/32535200","citation_count":4,"is_preprint":false},{"pmid":"23740402","id":"PMC_23740402","title":"LIN7-IRSp53: A novel pathway for filopodia and neurite formation?","date":"2012","source":"Communicative & integrative biology","url":"https://pubmed.ncbi.nlm.nih.gov/23740402","citation_count":3,"is_preprint":false},{"pmid":"23872532","id":"PMC_23872532","title":"Membrane binding properties of IRSp53-missing in metastasis domain (IMD) protein.","date":"2013","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/23872532","citation_count":3,"is_preprint":false},{"pmid":"40472834","id":"PMC_40472834","title":"ADAMTS5 Modulates Breast Cancer Development as a Diagnostic Biomarker and Potential Tumour Suppressor, Regulated by BAIAP2-AS1, CRNDE and hsa-miR-135b-3p: Integrated Systems Biology and Experimental Approach.","date":"2025","source":"IET systems biology","url":"https://pubmed.ncbi.nlm.nih.gov/40472834","citation_count":1,"is_preprint":false},{"pmid":"36943331","id":"PMC_36943331","title":"Negatively curved cellular membranes promote BAIAP2 signaling hub assembly.","date":"2023","source":"Nanoscale","url":"https://pubmed.ncbi.nlm.nih.gov/36943331","citation_count":1,"is_preprint":false},{"pmid":"35923471","id":"PMC_35923471","title":"Identification of a Rare BAIAP2-ROS1 Fusion and Clinical Benefit of Crizotinib in the Treatment of Advanced Lung Adenocarcinoma: A Case Report.","date":"2022","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/35923471","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47433,"output_tokens":10789,"usd":0.152067,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":21341,"output_tokens":6275,"usd":0.13179,"stage2_stop_reason":"end_turn"},"total_usd":0.283857,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"Activated Rac binds to the N-terminal domain of IRSp53, and the C-terminal SH3 domain of IRSp53 binds to WAVE, forming a trimolecular Rac–IRSp53–WAVE complex that is essential for Rac-induced membrane ruffling.\",\n      \"method\": \"Co-immunoprecipitation, ectopic expression, domain-binding assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays plus functional rescue experiments, replicated across multiple subsequent studies\",\n      \"pmids\": [\"11130076\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Cdc42 binds to a partial CRIB motif in IRSp53, relieving an intramolecular autoinhibitory interaction between the CRIB-containing central region and the N-terminal domain, thereby allowing the SH3 domain to recruit Mena; the resulting IRSp53–Mena complex promotes filopodia formation.\",\n      \"method\": \"Affinity chromatography, co-immunoprecipitation, dominant-negative expression, filopodia formation assay in fibroblasts\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (affinity chromatography, Co-IP, dominant-negative rescue) in a single study, widely replicated\",\n      \"pmids\": [\"11696321\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The SH3 domain of BAIAP2/IRSp53 directly binds to a proline-rich cytoplasmic fragment of BAI1 (brain-specific angiogenesis inhibitor 1), and co-expression with BAI1 recruits BAIAP2 to the cytoplasmic membrane.\",\n      \"method\": \"Yeast two-hybrid, in vitro binding assay, double-color immunofluorescence in COS-7 cells\",\n      \"journal\": \"Cytogenetics and Cell Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid confirmed by in vitro binding and co-localization, single lab\",\n      \"pmids\": [\"10343108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The proline-rich FH1 domain of mDia1 binds the SH3 domain of IRSp53/BAIAP2 in a GTP-Rho-dependent manner, identifying IRSp53 as a downstream effector of mDia1.\",\n      \"method\": \"Pulldown assay, co-immunoprecipitation with GTP-Rho\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct pulldown with GTPase-dependency shown, single lab, single method\",\n      \"pmids\": [\"10814512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The SH3 domain of IRSp53 interacts with a proline-rich sequence in ProSAP/Shank family members, and the IRSp53–Shank complex is co-immunoprecipitated from rat brain membranes; active Cdc42 regulates coprecipitation of IRSp53 with Shank1.\",\n      \"method\": \"Yeast two-hybrid, Co-IP from rat brain, mutational analysis, co-expression in COS cells\",\n      \"journal\": \"Journal of Neurochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — interaction confirmed by Co-IP from native brain tissue plus mutagenesis to map binding site, replicated by two independent labs\",\n      \"pmids\": [\"12421375\", \"12504591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The SH3 domain of IRSp53 interacts with proline-rich residues 911–940 of Shank1; co-expression of Shank1 with IRSp53 in HEK cells prevents IRSp53 targeting to filopodia, and this redistribution is regulated by active Cdc42.\",\n      \"method\": \"Yeast two-hybrid, overlay assay, co-expression in HEK cells, pulldown with GTPase\",\n      \"journal\": \"Molecular and Cellular Neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — overlay assay plus cellular localization assay, single lab, no reciprocal Co-IP from tissue\",\n      \"pmids\": [\"12504591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"IRSp53 localizes specifically to the tips of protruding lamellipodia and filopodia via its N-terminal Rac-binding domain, and co-localizes with WAVE2 at these sites during protrusion.\",\n      \"method\": \"Live-cell imaging of EGFP-tagged IRSp53 and DsRed-WAVE2, antibody labeling, deletion mutant analysis\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live-cell imaging with multiple deletion constructs to map localization determinant, co-localization with WAVE2 demonstrated in two conditions\",\n      \"pmids\": [\"12734400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"IRSp53 directly binds Eps8 via its SH3 domain and the N-terminal proline-rich region of Eps8; the IRSp53–Eps8 complex forms at the leading edge of motile cells and synergistically activates Rac by reinforcing formation of the Eps8/Abi-1/Sos-1 GEF complex.\",\n      \"method\": \"Co-immunoprecipitation, direct binding assay, FRET analysis in live cells, invasion/motility assays\",\n      \"journal\": \"Cancer Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP of endogenous proteins plus direct binding, FRET confirmation of complex at leading edge, functional rescue, replicated in subsequent studies\",\n      \"pmids\": [\"15289329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The crystal structure of the IRSp53 IMD (I-BAR domain) reveals a zeppelin-shaped coiled-coil dimer; mutagenesis of conserved basic residues at the dimer tips abrogates F-actin bundling in vitro and filopodia formation in vivo, establishing that IMD-mediated actin bundling is required for filopodia induction.\",\n      \"method\": \"X-ray crystallography, analytical ultracentrifugation, in vitro actin bundling assay, site-directed mutagenesis, filopodia formation assay\",\n      \"journal\": \"The EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus in vitro reconstitution of actin bundling plus mutagenesis and in vivo filopodia assay in one study\",\n      \"pmids\": [\"15635447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Tiam1 binds IRSp53 and directs it toward Rac (rather than Cdc42) signaling by enhancing IRSp53 binding to active Rac and the WAVE2 scaffold; IRSp53 depletion prevents Tiam1-dependent lamellipodia formation.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, lamellipodia formation assays, PDGF stimulation\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus RNAi-based functional rescue, single lab\",\n      \"pmids\": [\"15899863\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IRSp53 optimizes WAVE2 complex-mediated Arp2/3 activation in a Rac- and PIP3-dependent manner on membranes; WAVE2 complex isolated from the membrane fraction (but not cytosol) is fully active in an IRSp53-dependent manner.\",\n      \"method\": \"RNAi knockdown, in vitro Arp2/3 activation assay with purified proteins and PIP3-liposomes, membrane fractionation\",\n      \"journal\": \"The Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified WAVE2 complex, IRSp53, Rac, and PIP3-liposomes; multiple conditions tested; single lab\",\n      \"pmids\": [\"16702231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Eps8 has intrinsic actin cross-linking activity and synergizes with IRSp53 for actin bundling in vitro; Cdc42 controls the cellular distribution of the IRSp53–Eps8 complex; Cdc42-induced filopodia require both IRSp53 and Eps8.\",\n      \"method\": \"In vitro actin bundling assay, Co-IP, RNAi knockdown, filopodia formation assay\",\n      \"journal\": \"Nature Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of actin bundling plus RNAi loss-of-function with specific filopodia phenotype, replicated\",\n      \"pmids\": [\"17115031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The RCB/IMD domain of IRSp53 induces membrane deformation (small buds) on liposomes in a Rac-dependent manner via its convex surface, opposite to the invaginations produced by BAR domains; this activity is independent of actin.\",\n      \"method\": \"Liposome deformation assay, crystal structure of RCB/IMD, mutational mapping of membrane-binding residues, cellular expression of domain constructs\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural data plus in vitro liposome deformation and Rac-dependency mapping, single lab\",\n      \"pmids\": [\"17003044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The N-terminal IMD (I-BAR domain) of IRSp53 directly binds PI(4,5)P2-rich membranes and deforms them into tubular structures with curvature opposite to BAR domains (negative curvature/outward protrusion); the membrane-deforming activity of the IMD, rather than its actin-bundling or GTPase-binding activities, is critical for filopodia/microspike induction.\",\n      \"method\": \"In vitro membrane tubulation assay with PI(4,5)P2 liposomes, electron microscopy, mutagenesis, cellular filopodia assay\",\n      \"journal\": \"The Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with defined lipid compositions plus mutagenesis separating activities, widely replicated\",\n      \"pmids\": [\"17371834\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Synaptopodin directly binds IRSp53 and suppresses Cdc42:IRSp53:Mena-initiated filopodia formation by blocking the binding of Cdc42 and Mena to IRSp53 in kidney podocytes.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, filopodia formation assay, siRNA knockdown, pharmacological Mena inhibition in vivo\",\n      \"journal\": \"The American Journal of Pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding confirmed by pulldown plus functional loss-of-function in cells and in vivo, single lab\",\n      \"pmids\": [\"17569780\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IRSp53 directly interacts with N-WASP via its SH3 domain; the I-BAR domain alone induces membrane protrusions lacking actin ('partial filopodia'), while full filopodia require SH3-domain partners (N-WASP and Mena/VASP); Mena/VASP but not N-WASP Arp2/3-activation activity is required for IRSp53-induced filopodia.\",\n      \"method\": \"Co-IP, RNAi knockdown in N-WASP KO and Mena/VASP KO fibroblasts, expression of domain mutants, filopodia reconstitution assay\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO fibroblast reconstitution plus multiple domain mutants, two independent KO cell lines tested\",\n      \"pmids\": [\"18448434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Par1b directly phosphorylates IRSp53 on S366 (and indirectly on S453/3/5), and a Par1b phosphorylation-deficient IRSp53 mutant rescues cell spreading and lumen polarity defects in Par1b-overexpressing MDCK cells, placing IRSp53 downstream of Par1b in cell-ECM signaling.\",\n      \"method\": \"In vitro kinase assay with cell lysates, site-directed mutagenesis, RNAi knockdown, rescue assays in MDCK cells\",\n      \"journal\": \"The Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct phosphorylation demonstrated in cell lysates with mutational validation and functional rescue, single lab\",\n      \"pmids\": [\"21282462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"LIN7 recruits IRSp53 to tight junctions via its PDZ domain; loss of LIN7 prevents TJ localization of IRSp53 and reduces Rac1 activation, causing defects in TJ assembly and epithelial cyst polarization.\",\n      \"method\": \"Dominant-negative LIN7 expression, shRNA knockdown, immunofluorescence, Co-IP, Rac1 activation assay\",\n      \"journal\": \"Traffic\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic tools (dominant-negative, shRNA) with functional phenotypes, single lab\",\n      \"pmids\": [\"19054385\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Tyrosine 310 in the central unstructured region of IRSp53 is the primary site of phosphorylation downstream of the insulin receptor; the N-terminal IMD domain is required for efficient tyrosine phosphorylation but is not itself phosphorylated.\",\n      \"method\": \"Truncation and point-mutant analysis with insulin/EGF stimulation, Western blotting for phosphotyrosine\",\n      \"journal\": \"European Journal of Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic mutagenesis to map phosphorylation site, single lab\",\n      \"pmids\": [\"18417251\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IRSp53 family members directly interact with both EHEC Tir (via residues 454–463) and EspFU, colocalizing with EspFU and N-WASP in actin pedestals; loss of IRSp53 abrogates EHEC actin assembly, identifying IRSp53 as the missing host factor linking Tir to EspFU.\",\n      \"method\": \"Co-IP, direct binding assay, genetic loss-of-function (IRSp53 KO cells), immunofluorescence colocalization\",\n      \"journal\": \"Cell Host & Microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding plus genetic KO with specific actin-assembly phenotype, replicated with dissection of Tir binding residues\",\n      \"pmids\": [\"19286134\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IRSp53 knockout mice display a selective increase in NMDA receptor-mediated synaptic transmission (but not AMPA) and markedly enhanced LTP, establishing that IRSp53 negatively regulates NMDA receptor function at excitatory synapses.\",\n      \"method\": \"IRSp53 knockout mice, electrophysiology (AMPA/NMDA ratio, LTP), immunoelectron microscopy of PSD\",\n      \"journal\": \"The Journal of Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with electrophysiological phenotype, replicated by multiple independent labs\",\n      \"pmids\": [\"19193906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Kank specifically inhibits the binding of IRSp53 to active Rac1 (but not Cdc42), thereby suppressing IRSp53-dependent lamellipodia formation without affecting filopodia.\",\n      \"method\": \"Co-IP, direct binding competition assay, RNAi double-knockdown, lamellipodia/filopodia formation assays\",\n      \"journal\": \"The Journal of Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP competition assay plus double-KD rescue experiment, single lab\",\n      \"pmids\": [\"19171758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"14-3-3 binding to phosphorylated residues T340 and T360 (between the CRIB and SH3 domains of IRSp53) inhibits SH3-domain interactions with WAVE2 and Eps8 and blocks Cdc42-GTP binding, extending filopodium lifetimes when these sites are mutated.\",\n      \"method\": \"Phosphorylation mapping, Co-IP, SH3 domain-swapping, live-cell filopodia dynamics imaging\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phospho-site mapping plus domain-swapping plus live-cell functional imaging, single lab\",\n      \"pmids\": [\"19933840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Postsynaptic Shank proteins compete with Eps8 for binding to IRSp53, blocking Eps8-IRSp53-dependent actin bundling; IRSp53 KO mice show decreased PSD size and increased NMDA receptor subunits at the PSD.\",\n      \"method\": \"IRSp53 KO mice, competitive binding assay, electrophysiology, LTP measurement\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — competitive binding with multiple proteins plus genetic KO mouse with electrophysiological and ultrastructural phenotypes, multi-method\",\n      \"pmids\": [\"19208628\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IRSp53 is required for Cdc42-dependent formation of basal filopodia that physically tether presumptive lens and retina to coordinate epithelial invagination during mouse eye development.\",\n      \"method\": \"IRSp53 (Baiap2) conditional KO mice, confocal and electron microscopy, filopodia quantification\",\n      \"journal\": \"Development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with specific morphogenetic phenotype in vivo, single lab\",\n      \"pmids\": [\"19820184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SPIN90 directly associates with the SH3 domain of IRSp53 via its proline-rich domain; the SPIN90–IRSp53 complex forms at the leading edge and cooperatively mediates Rac activation and membrane ruffle formation.\",\n      \"method\": \"Co-IP, direct binding assay, siRNA knockdown, competitive inhibition, PDGF stimulation assay\",\n      \"journal\": \"Experimental Cell Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct binding confirmed, siRNA knockdown with functional phenotype, single lab\",\n      \"pmids\": [\"19460367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Tiam1 interacts with both IRSp53 and spinophilin to generate spatially localized Rac activation; IRSp53-dependent Rac activation mediates cell ruffling, spreading, and adhesion, whereas spinophilin-dependent Rac activation mediates cell migration.\",\n      \"method\": \"FRET-based Rac activity assay, RNAi knockdown, cell adhesion/spreading assays, signaling measurements\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET-based localized Rac activity measurement plus RNAi, single lab\",\n      \"pmids\": [\"20360004\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"mDia1 and WAVE2 directly interact with IRSp53 within filopodia (confirmed by acceptor-photobleaching FRET); mDia1 and WAVE2 synergize specifically with IRSp53 (not mDia2 or WAVE1) to promote filopodia formation in neuronal cells.\",\n      \"method\": \"FRET (acceptor photobleaching), RNAi knockdown, time-lapse imaging of filopodia formation\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET confirmation of direct interaction within filopodia plus selective RNAi knockdown with time-lapse phenotyping, single lab\",\n      \"pmids\": [\"22179776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The crystal structure of the IRSp53 I-BAR domain in complex with a Tir-derived NPY peptide shows the homodimeric I-BAR binding two parallel Tir molecules; the NPY motif is specifically recognized by a conserved binding site on the I-BAR surface, confirmed by mutagenesis and in vivo binding assays.\",\n      \"method\": \"X-ray crystallography, site-directed mutagenesis, in vivo binding assay\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with mutagenesis validation and in vivo binding confirmation, single lab\",\n      \"pmids\": [\"21893288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRSp53 depletion reduces Rac1-dependent surface ruffling and CSF-1-induced actin polymerization and cell migration in macrophages; IRSp53 forms an immunoprecipitable complex with WAVE2 and Abi1 in a Rac1-activation-dependent manner, and IRSp53 is required for Rac1 association with WAVE2/Abi1.\",\n      \"method\": \"RNAi knockdown, Co-IP, Rac1Q61L expression, phagocytosis/protrusion assays\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi plus Rac-dependency Co-IP in macrophages with multiple functional readouts, single lab\",\n      \"pmids\": [\"18198193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LIN7 binding to the C-terminal PDZ-binding motif of IRSp53 is required for formation of actin-filled filopodia and neurites in neuronal cells; LIN7 silencing prevents IRSp53 incorporation into Triton X-100-insoluble (membrane-associated) complexes in differentiated cells.\",\n      \"method\": \"LIN7 siRNA knockdown, chimeric protein expression, live-cell imaging, Triton X-100 fractionation, neurite outgrowth assay\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and chimeric rescue experiments plus biochemical fractionation, single lab\",\n      \"pmids\": [\"22767515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CDC42 switches IRSp53 from inhibiting actin filament barbed-end growth to promoting VASP clustering; IRSp53 inhibits barbed-end growth, which is relieved by CDC42; IRSp53-dependent VASP clustering drives processive actin elongation for filopodia initiation; IRSp53 null mice display defective wound healing.\",\n      \"method\": \"In vitro actin polymerization assays, TIRF microscopy, liposome binding, IRSp53 KO mice wound healing assay, filopodia dynamics imaging\",\n      \"journal\": \"The EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with single-molecule TIRF plus multiple KO phenotypes, mechanistic dissection of VASP clustering\",\n      \"pmids\": [\"24076653\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"IRSp53 knockdown attenuates podosome formation and migration in Src-transformed cells; IRSp53 physically interacts with VASP and links small GTPases to VASP for podosome formation; C-terminal splicing isoforms of IRSp53 do not affect this function.\",\n      \"method\": \"RNAi knockdown, Co-IP, podosome formation assay, cell migration assay, deletion mutant expression\",\n      \"journal\": \"PLoS One\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus RNAi with specific podosome phenotype, single lab\",\n      \"pmids\": [\"23555988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dynamin1 is an IRSp53-interacting partner that localizes to filopodia tips during initiation and assembly; dynamin GTPase activity and its actin-binding domain are required for filopodia formation, placing Dyn1 downstream of IRSp53 in a Dyn1–Mena–Eps8 regulatory network.\",\n      \"method\": \"Pulldown, FRET, RNAi knockdown, pharmacological inhibition (dynasore), TIRF live-cell imaging, expression of GTPase mutants\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET confirmation of interaction plus multiple genetic/pharmacological perturbations with live-cell dynamics, single lab\",\n      \"pmids\": [\"25031323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRSp53 knockout mice display enhanced NMDA receptor function in the hippocampus; treatment with the NMDAR antagonist memantine or the mGluR5 antagonist MPEP normalizes social interaction and NMDAR function/plasticity, establishing a causal link between elevated NMDAR activity and social deficits caused by IRSp53 loss.\",\n      \"method\": \"IRSp53 KO mice, behavioral testing, electrophysiology, pharmacological rescue with memantine/MPEP\",\n      \"journal\": \"Nature Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO plus pharmacological rescue with electrophysiological and behavioral correlates, replicated across multiple labs\",\n      \"pmids\": [\"25622145\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRSp53 senses negative membrane curvature via its I-BAR domain; I-BAR dimers display non-monotonic curvature sorting, constricting weakly curved tubes at low tension while expanding them at high tension; at low protein density and tension, protein-rich domains form along membrane tubes.\",\n      \"method\": \"Protein encapsulation in giant unilamellar vesicles connected to membrane nanotubes, theoretical modeling\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — original biophysical reconstitution assay with quantitative theory, demonstrates curvature sensing mechanistically\",\n      \"pmids\": [\"26469246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRSp53 is involved in the Rac1–IRSp53–WAVE2–Arp2/3 signaling pathway; siRNA knockdown of IRSp53 decreases HIV-1 Gag membrane localization and viral particle release in CD4 T cells.\",\n      \"method\": \"siRNA knockdown, immunofluorescence confocal microscopy, membrane flotation assay, immunoblot\",\n      \"journal\": \"Journal of Virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi with multiple orthogonal readouts (membrane fractionation, immunofluorescence, particle production), single lab\",\n      \"pmids\": [\"26018170\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"14-3-3 binds to two pairs of phosphorylation sites in IRSp53; each IRSp53 subunit independently binds one 14-3-3 dimer; 14-3-3 binding causes conformational changes (opposite to activatory Cdc42/Eps8 inputs) and inhibits IRSp53 binding to membranes and to Cdc42/downstream effectors.\",\n      \"method\": \"Phosphoproteomics, quantitative binding assays, crystallography of 14-3-3:phosphopeptide complexes, FRET-sensor assay with bicistronic heterodimer expression\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus FRET conformational sensor plus quantitative binding with mutagenesis, multiple orthogonal methods in one study\",\n      \"pmids\": [\"30696821\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"AMPK phosphorylates two of the three 14-3-3 binding sites in IRSp53; pharmacological AMPK activation increases IRSp53 phosphorylation and 14-3-3 binding, inhibiting filopodia dynamics and cancer cell chemotaxis; mutating these sites reverses 14-3-3 inhibition.\",\n      \"method\": \"Pharmacological AMPK activation/inhibition, phosphorylation site mutagenesis, live-cell filopodia dynamics imaging, cancer cell chemotaxis assay\",\n      \"journal\": \"Molecular Biology of the Cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological and mutational evidence for AMPK as the kinase, functional filopodia and migration readouts, single lab\",\n      \"pmids\": [\"30893014\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IRSp53 controls lumen formation and positioning of polarity determinants (aPKC, podocalyxin) by regulating RAB35 localization/activity and by interacting with EPS8; IRSp53 genetic removal causes abnormal renal tubulogenesis with altered tubular polarity.\",\n      \"method\": \"IRSp53 KO mouse model, correlative light and electron microscopy (CLEM), Co-IP, RAB35 activity assay\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO in vivo plus CLEM plus RAB35 functional interaction, multiple orthogonal methods\",\n      \"pmids\": [\"32665580\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"IRSp53 I-BAR domain is required for progression of HIV-1 membrane curvature during particle assembly; siRNA knockdown of IRSp53 arrests viral bud at half completion; IRSp53 is found in purified HIV-1 particles and is enriched around Gag assembly sites; HIV-1 Gag localizes preferentially to I-BAR-induced membrane curvature on GUVs.\",\n      \"method\": \"siRNA knockdown, single-molecule localization microscopy, GUV curvature assay, purification of HIV-1 particles with mass spectrometry\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (super-resolution microscopy, GUV reconstitution, purified virion proteomics) plus RNAi loss-of-function with specific structural phenotype\",\n      \"pmids\": [\"34114563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Full-length IRSp53 self-assembles into clusters on membranes in a PIP2-dependent manner; IRSp53 clusters recruit VASP to locally assemble actin filaments and generate actin-filled membrane protrusions resembling filopodia in vitro; IRSp53 is enriched and triggers actin assembly only at highly dynamic membrane regions in live cells.\",\n      \"method\": \"In vitro reconstitution with GUVs and supported bilayers, live-cell membrane nanotube pulling, TIRF microscopy, molecular dynamics simulation\",\n      \"journal\": \"Science Advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — full in vitro reconstitution of filopodium-like protrusions with defined components plus live-cell validation and MD simulation, multiple orthogonal methods\",\n      \"pmids\": [\"36240267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Multivalent interactions between IRSp53 and PSD-95 or Shank3 drive liquid-liquid phase separation; IRSp53 is enriched in reconstituted excitatory PSD condensates via bridging to core and deeper PSD layers; PSD condensates promote bundled actin filament formation on membranes via IRSp53-mediated actin binding and bundling; disruption of IRSp53–actin interaction causes synaptic maturation defects in cortical neurons.\",\n      \"method\": \"Phase separation assay (in vitro droplet formation), PSD reconstitution, actin bundling assay on membranes, mutant overexpression in mouse cortical neurons\",\n      \"journal\": \"The Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of phase separation and actin bundling with defined components plus neuronal functional validation, single lab multi-method study\",\n      \"pmids\": [\"35819332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Eps8 forms heightened interactions with IRSp53 upon Arp2/3 inhibition, and the Eps8–IRSp53 complex drives linear actin polymerization required for tunnelling nanotube (TNT) formation over long distances.\",\n      \"method\": \"Micropatterning, optical tweezers, proteomics (Eps8 interactome upon Arp2/3 inhibition), RNAi knockdown, time-lapse microscopy\",\n      \"journal\": \"The EMBO Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomic interaction shift plus optical tweezers functional assay, single lab\",\n      \"pmids\": [\"38009333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"IRSp53 mediates coupling of actin filaments to the plasma membrane at protrusive tips during cell migration on 1D fibers; IRSp53 depletion reduces actin stress fibers originating from cell periphery and uncouples nuclear movement from cell motility; IRSp53 controls retrograde actin flow at cell edges.\",\n      \"method\": \"RNAi knockdown, speckle microscopy for retrograde actin flow, live-cell migration assay on suspended 1D nanofibers, theoretical modeling\",\n      \"journal\": \"Advanced Science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi with quantitative actin flow measurements and migration assay in defined 1D geometry, single lab\",\n      \"pmids\": [\"36698307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A de novo BAIAP2 variant p.Arg29Trp (in the I-BAR domain) causes a loss-of-function defect by preventing IRSp53 membrane localization; in utero electroporation of Baiap2 knockdown or expression of the variant causes abnormal neuronal migration, morphogenesis, and differentiation in the developing mouse cortex.\",\n      \"method\": \"In utero electroporation (knockdown and variant rescue), spatial transcriptomics, membrane localization assay\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function and variant rescue in vivo in developing brain plus mechanistic identification of membrane localization defect\",\n      \"pmids\": [\"38149472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BIN1-mediated filopodia formation requires IRSp53; BIN1 colocalizes with F-actin along filopodia and bundles actin in vitro; BIN1 recruits actin-binding proteins (dynamin, ezrin) to negatively-curved membrane topologies in an IRSp53-dependent manner.\",\n      \"method\": \"RNAi knockdown, in vitro actin bundling assay, Co-IP, immunofluorescence colocalization\",\n      \"journal\": \"Communications Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro actin bundling plus RNAi dependency assay, single lab\",\n      \"pmids\": [\"38724689\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Robo2 binds directly to BAIAP2/IRSp53 through the I-BAR/IMD domain in renal epithelial cells; the Robo2–BAIAP2 complex allows Robo2 to phosphorylate MDM2 at Ser166 via BAIAP2, maintaining p53 homeostasis; disruption of this complex leads to MDM2 dephosphorylation, p53 accumulation, cellular senescence and cystic kidney disease.\",\n      \"method\": \"Co-IP, double KO mouse model, phosphorylation assay, rescue experiments\",\n      \"journal\": \"JCI Insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus genetic double-KO rescue plus phosphorylation assay, single lab\",\n      \"pmids\": [\"31534052\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IRSp53/BAIAP2 is a multidomain I-BAR scaffolding protein that senses and generates negative membrane curvature (outward protrusions) via its PIP2-binding I-BAR domain, recruits actin regulatory proteins (WAVE2, Mena/VASP, Eps8, N-WASP, mDia1) through its SH3 domain downstream of Rac and Cdc42 GTPases, and bridges membrane deformation with actin polymerization to initiate filopodia and lamellipodia; at excitatory synapses it is incorporated into PSD condensates via Shank and PSD-95 interactions to limit NMDA receptor density and synaptic plasticity, while its activity is tuned by phosphorylation-dependent 14-3-3 binding (inhibitory), Par1b-mediated phosphorylation, and competition among SH3-domain partners.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BAIAP2 (IRSp53) is a multidomain scaffold that couples plasma-membrane deformation to actin polymerization, acting as the central node linking Rho-family GTPase signaling to the formation of filopodia, lamellipodia, and other membrane protrusions [#0, #1, #13]. Its N-terminal I-BAR (IMD) domain binds PI(4,5)P2-rich membranes and deforms them into outward (negative-curvature) protrusions opposite to classical BAR domains, and this membrane-deforming activity—rather than actin bundling per se—is the critical determinant of filopodium induction [#13, #12]; biophysical reconstitution shows the I-BAR dimer senses negative membrane curvature in a tension-dependent manner [#35]. The C-terminal SH3 domain recruits a competing repertoire of actin regulators—WAVE2, Mena/VASP, Eps8, N-WASP, mDia1, and SPIN90—downstream of activated Rac and Cdc42, with GTPase binding relieving an intramolecular autoinhibition to license SH3 engagement [#0, #1, #7, #15, #27]. IRSp53 optimizes Rac/PIP3-dependent WAVE2–Arp2/3 activation on membranes [#10] and, when clustered on PIP2 membranes, recruits VASP to drive processive actin elongation that builds filopodium-like protrusions in fully reconstituted systems [#41, #31]. Its activity is tuned by inhibitory phosphorylation-dependent 14-3-3 binding, which blocks membrane and Cdc42/effector engagement and is set by kinases including AMPK [#37, #22, #38]. At excitatory synapses, IRSp53 is incorporated into PSD condensates through multivalent interactions with Shank and PSD-95 and limits NMDA receptor density and synaptic plasticity; its loss in mice enhances NMDAR-mediated transmission and produces social deficits reversible by NMDAR/mGluR5 antagonism [#23, #42, #20, #34]. The protein also serves morphogenetic roles in epithelial lumen formation and cortical neuronal migration, and is exploited by pathogens—bridging EHEC Tir/EspFU to actin pedestals and shaping HIV-1 membrane curvature during budding [#39, #45, #19, #40]. A de novo I-BAR domain variant (p.Arg29Trp) that abolishes membrane localization causes neurodevelopmental defects, establishing a direct link between IRSp53 membrane targeting and cortical development [#45].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established IRSp53 as the physical bridge connecting active Rac to the WAVE actin nucleation machinery, defining its core role as a GTPase-to-actin adaptor.\",\n      \"evidence\": \"Co-IP and domain-binding assays reconstituting a Rac–IRSp53–WAVE trimolecular complex driving membrane ruffling\",\n      \"pmids\": [\"11130076\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how membrane binding integrates with this complex\", \"Structural basis of the Rac-binding region not defined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Showed that Cdc42 binding relieves an intramolecular autoinhibition to license SH3-mediated effector recruitment, explaining GTPase-dependent switching toward filopodia.\",\n      \"evidence\": \"Affinity chromatography, Co-IP, dominant-negative expression and filopodia assays in fibroblasts identifying the IRSp53–Mena complex\",\n      \"pmids\": [\"11696321\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic mechanism of autoinhibition relief not defined\", \"Quantitative competition among SH3 partners not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identified Shank/ProSAP as a postsynaptic SH3 partner of IRSp53, anchoring it to the PSD and revealing Cdc42-regulated synaptic localization.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP from rat brain membranes, and mutational mapping; cellular redistribution assays in HEK cells\",\n      \"pmids\": [\"12421375\", \"12504591\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence at synapses not yet measured\", \"Did not establish PSD condensate context\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined the IRSp53–Eps8 complex at the leading edge as a positive amplifier of Rac signaling, linking membrane protrusion to GEF activation.\",\n      \"evidence\": \"Co-IP, direct binding, FRET in live cells, and invasion/motility assays\",\n      \"pmids\": [\"15289329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve competition with other SH3 partners\", \"In vivo relevance of leading-edge complex untested\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Crystal structure of the I-BAR (IMD) domain revealed a zeppelin-shaped coiled-coil dimer and tied basic-tip residues to actin bundling and filopodia induction.\",\n      \"evidence\": \"X-ray crystallography, analytical ultracentrifugation, in vitro actin bundling, and filopodia assays with mutagenesis\",\n      \"pmids\": [\"15635447\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Membrane-deformation role of the domain not yet separated from actin bundling\", \"Relative contribution of bundling vs curvature unresolved at this stage\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the central mechanism by showing the I-BAR domain binds PI(4,5)P2 and generates outward (negative) membrane curvature, the activity critical for filopodium induction—distinct from actin bundling.\",\n      \"evidence\": \"In vitro PI(4,5)P2 liposome tubulation, electron microscopy, mutagenesis separating activities, and cellular filopodia assays\",\n      \"pmids\": [\"17371834\", \"17003044\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How membrane curvature is coupled in time to actin assembly not yet reconstituted\", \"Tension dependence of curvature activity not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated that the I-BAR domain alone makes actin-free protrusions while SH3 partners (N-WASP, Mena/VASP) are required for full filopodia, partitioning the membrane-shaping and actin-elongating functions.\",\n      \"evidence\": \"Co-IP and reconstitution in N-WASP and Mena/VASP knockout fibroblasts with domain mutants\",\n      \"pmids\": [\"18448434\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify which elongation mechanism dominates in vivo\", \"Regulation of partner selection unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Genetic knockout established IRSp53 as a negative regulator of NMDA receptor function and synaptic plasticity, embedding it in postsynaptic Shank/Eps8 competition that controls PSD composition.\",\n      \"evidence\": \"IRSp53 KO mice with electrophysiology (AMPA/NMDA ratio, LTP), immuno-EM of PSD, and competitive binding assays\",\n      \"pmids\": [\"19193906\", \"19208628\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of NMDAR restriction not fully defined\", \"Link to behavior not yet established at this stage\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Revealed multiple negative regulators (14-3-3, Kank, synaptopodin) that selectively gate IRSp53 toward Rac- or Cdc42-driven protrusions, establishing combinatorial control of its output.\",\n      \"evidence\": \"Phospho-site mapping, Co-IP competition, RNAi, and live-cell filopodia/lamellipodia assays\",\n      \"pmids\": [\"19933840\", \"19171758\", \"17569780\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinases setting 14-3-3 sites not yet identified\", \"Structural basis of 14-3-3 inhibition unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed IRSp53 is the host factor coupling EHEC Tir to EspFU and N-WASP for actin pedestal assembly, extending its adaptor role to pathogen-driven actin polymerization.\",\n      \"evidence\": \"Co-IP, direct binding, IRSp53 KO cells, and immunofluorescence colocalization in actin pedestals\",\n      \"pmids\": [\"19286134\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural recognition of the Tir NPY motif not yet defined (resolved later)\", \"Generality to other I-BAR proteins untested here\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Crystallography of the I-BAR–Tir NPY peptide complex defined a conserved surface binding site, providing structural detail for pathogen hijacking of IRSp53.\",\n      \"evidence\": \"X-ray crystallography with mutagenesis and in vivo binding validation\",\n      \"pmids\": [\"21893288\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether host ligands use the same I-BAR surface not addressed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reconstitution revealed the GTPase switch at the actin barbed end: IRSp53 inhibits barbed-end growth until CDC42 relieves it and converts IRSp53 into a VASP-clustering factor driving processive elongation, with in vivo wound-healing requirement.\",\n      \"evidence\": \"In vitro actin polymerization, single-molecule TIRF, liposome binding, and IRSp53 KO mouse wound-healing assays\",\n      \"pmids\": [\"24076653\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of VASP clustering on membranes not defined here\", \"How phosphoregulation intersects this switch not addressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Quantified the biophysics of I-BAR curvature sensing, showing tension-dependent, non-monotonic sorting and density-dependent domain formation on membrane tubes.\",\n      \"evidence\": \"Protein encapsulation in GUVs connected to membrane nanotubes with theoretical modeling\",\n      \"pmids\": [\"26469246\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coupling of sensing to actin assembly not reconstituted in this system\", \"Full-length protein behavior not yet tested here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linked elevated NMDAR activity to behavioral deficits by showing NMDAR/mGluR5 antagonists rescue social impairments in IRSp53 KO mice, establishing causal relevance to circuit function.\",\n      \"evidence\": \"IRSp53 KO mice with behavioral testing, electrophysiology, and pharmacological rescue (memantine/MPEP)\",\n      \"pmids\": [\"25622145\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism limiting NMDAR density not fully defined\", \"Cell-type specificity of the deficit unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined the structural and conformational basis of 14-3-3 inhibition and identified AMPK as a kinase setting these sites, providing a metabolic input that suppresses filopodia and chemotaxis.\",\n      \"evidence\": \"Phosphoproteomics, crystallography of 14-3-3:phosphopeptide complexes, FRET conformational sensors, and pharmacological AMPK modulation with site mutants\",\n      \"pmids\": [\"30696821\", \"30893014\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full set of physiological kinases at these sites not enumerated\", \"Dynamics of 14-3-3 release in cells not measured\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended IRSp53 function to epithelial morphogenesis, showing it controls lumen formation and apical polarity via RAB35 and EPS8 in renal tubulogenesis.\",\n      \"evidence\": \"IRSp53 KO mouse, CLEM, Co-IP, and RAB35 activity assays\",\n      \"pmids\": [\"32665580\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking membrane curvature to RAB35 regulation unresolved\", \"Whether actin assembly is required not fully separated\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated that the I-BAR domain shapes HIV-1 membrane curvature during budding, with Gag enriching at I-BAR-induced curvature, identifying a viral exploitation of IRSp53 curvature activity.\",\n      \"evidence\": \"siRNA knockdown, single-molecule localization microscopy, GUV curvature assays, and proteomics of purified virions\",\n      \"pmids\": [\"34114563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct Gag–IRSp53 contact not defined\", \"Whether actin machinery contributes to budding unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Achieved full reconstitution of IRSp53-driven filopodium-like protrusions, showing PIP2-dependent self-clustering recruits VASP for local actin assembly at dynamic membrane regions.\",\n      \"evidence\": \"In vitro reconstitution on GUVs and supported bilayers, membrane nanotube pulling, TIRF, live-cell imaging, and MD simulation\",\n      \"pmids\": [\"36240267\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regulatory inputs not included in minimal system\", \"Quantitative threshold for clustering in cells not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed IRSp53 partitions into PSD liquid-liquid phase-separated condensates via PSD-95/Shank3 bridging and links these condensates to membrane-associated actin bundling required for synapse maturation.\",\n      \"evidence\": \"In vitro droplet/PSD reconstitution, actin bundling assays on membranes, and mutant expression in mouse cortical neurons\",\n      \"pmids\": [\"35819332\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How condensate incorporation tunes NMDAR density mechanistically not resolved\", \"In vivo relevance of phase separation untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected IRSp53 to neurodevelopmental disease by showing a de novo I-BAR variant (p.Arg29Trp) abolishes membrane localization and disrupts cortical neuronal migration and morphogenesis.\",\n      \"evidence\": \"In utero electroporation knockdown and variant rescue, spatial transcriptomics, and membrane localization assays in developing mouse cortex\",\n      \"pmids\": [\"38149472\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human clinical spectrum not defined from this study\", \"Downstream actin pathway altered by the variant not mapped\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the competing inputs (GTPases, phosphorylation/14-3-3, SH3 partner competition, membrane tension, and phase separation) are integrated to determine when and where IRSp53 builds a specific protrusion type in vivo remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No unified model coupling membrane tension, GTPase state, and phosphoregulation in living cells\", \"Quantitative rules for SH3-partner selection in different cell types unknown\", \"Mechanism by which IRSp53 restricts synaptic NMDAR density not molecularly defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 7, 15, 17, 30]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [13, 12, 35, 41]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [8, 11, 31, 42]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [8, 13, 35, 41]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [10, 21, 22, 37]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 6, 13, 41]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6, 8, 31, 44]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [23, 42]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 10, 26]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [20, 23, 34, 42]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [24, 39, 45]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [19, 36, 40, 47]}\n    ],\n    \"complexes\": [\n      \"Rac–IRSp53–WAVE2 complex\",\n      \"IRSp53–Eps8 complex\",\n      \"WAVE2/Abi1–IRSp53 complex\",\n      \"PSD (PSD-95/Shank) condensate\"\n    ],\n    \"partners\": [\n      \"WASF2\",\n      \"EPS8\",\n      \"ENAH\",\n      \"SHANK1\",\n      \"DLG4\",\n      \"DIAPH1\",\n      \"WASL\",\n      \"BAI1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}