{"gene":"MPRIP","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":2003,"finding":"MPRIP (p116Rip) is a filamentous actin-binding protein that localizes to F-actin-rich structures (stress fibers, cortical microfilaments) via its N-terminal region (residues 1-382), binds F-actin with Kd ~0.5 µM, bundles F-actin in vitro, and is complexed with both F-actin and myosin-II in cells. Overexpression disrupts stress fibers and inhibits growth factor-induced lamellipodia formation.","method":"F-actin co-sedimentation, immunoprecipitation, electron microscopy of F-actin bundles, live/fixed cell imaging with deletion mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (biochemical binding assay, EM, IP, cell imaging with domain mutants) in a single study","pmids":["12732640"],"is_preprint":false},{"year":2004,"finding":"MPRIP (p116Rip) activates the GTPase activity of RhoA in vitro (acting as a GAP-like regulator) and reduces GTP-bound RhoA levels in cells after EGF stimulation. It also activates myosin light chain phosphatase (MLCP) holoenzyme activity specifically toward myosin as substrate by binding the myosin phosphatase targeting subunit MYPT1 and directly binding myosin, thereby facilitating myosin/MLCP interaction. Gene silencing of p116Rip increases myosin phosphorylation and stress fiber formation.","method":"In vitro GTPase assay, RhoA-GTP pulldown in cells, in vitro phosphatase activity assay, siRNA knockdown with phospho-MLC immunostaining","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro biochemical assays combined with cell-based siRNA knockdown and multiple readouts, single rigorous study","pmids":["15545284"],"is_preprint":false},{"year":2004,"finding":"MPRIP (p116Rip) interacts directly with the C-terminal leucine zipper of the regulatory myosin-binding subunits of myosin II phosphatase (MBS85 and MBS130) via its C-terminal coiled-coil domain, and targets the myosin phosphatase complex to the actin cytoskeleton. RNAi-mediated knockdown of p116Rip inhibits cell spreading and neurite outgrowth in response to extracellular cues without altering myosin light chain phosphorylation.","method":"Direct protein interaction assays (co-IP, domain mapping), RNAi knockdown with morphological readouts (cell spreading, neurite outgrowth)","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal interaction assays with domain mutants plus RNAi phenotype, replicated binding finding from other labs","pmids":["15469989"],"is_preprint":false},{"year":2005,"finding":"MPRIP (M-RIP) targets myosin phosphatase (via its myosin binding subunit MYPT1) to actin-myosin stress fibers in vascular smooth muscle cells. RNAi silencing of M-RIP reduced stress fiber localization of MYPT1, increased basal and LPA-stimulated myosin light chain phosphorylation, increased stress fiber numbers and cell area, and reduced stress fiber inhibition by a Rho-kinase inhibitor, without changing total cellular myosin phosphatase, MLCK, or RhoA activities.","method":"siRNA knockdown, immunofluorescence localization, phospho-MLC quantification, Rho-kinase inhibitor functional assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — clean siRNA with multiple orthogonal cellular readouts, consistent with parallel studies in other cell types","pmids":["16257966"],"is_preprint":false},{"year":2005,"finding":"MPRIP (p116Rip) oligomerizes via its C-terminal coiled-coil domain and inhibits RhoA-induced SRF transcriptional activation by disassembling the actomyosin cytoskeleton downstream of RhoA, independently of effects on RhoA-GTP levels. Mutant forms unable to oligomerize or bind MBS still inhibit SRF activity.","method":"Overexpression with SRF reporter assay, domain mutant analysis, RhoA-GTP pulldown","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, overexpression system with reporter assay and mutants but no in vitro reconstitution","pmids":["16243315"],"is_preprint":false},{"year":2008,"finding":"MPRIP (M-RIP) expression is induced downstream of JNK1 signaling in response to EGF, and siRNA-mediated knockdown of M-RIP significantly reduces the invasive activity of HeLa cancer cells.","method":"siRNA knockdown, microarray gene expression, Matrigel invasion assay","journal":"International journal of molecular medicine","confidence":"Low","confidence_rationale":"Tier 3 — single lab, single method for invasion phenotype, pathway placement based on expression change only","pmids":["18636174"],"is_preprint":false},{"year":2012,"finding":"MPRIP (M-RIP) associates with the PDZ protein syntenin-1 in a manner dependent on Src-mediated phosphorylation of syntenin-1 at Tyr4. This MPRIP-syntenin-1 complex is required for polarized Rac-1 activation and actin polymerization at the leading edge and immune synapse during T cell chemotaxis and APC interactions.","method":"Co-IP, mutant analysis, siRNA knockdown, GTPase activity assays, confocal microscopy of actin polarization","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2-3 — co-IP with phospho-mutants and siRNA phenotype, single lab","pmids":["22349701"],"is_preprint":false},{"year":2014,"finding":"PKG phosphorylates MPRIP (M-RIP), which enhances the association of MPRIP with MYPT1 and increases MLCP activity, leading to MLC20 dephosphorylation and muscle relaxation in gastric smooth muscle cells, operating downstream of both Ca2+- and RhoA-dependent pathways.","method":"siRNA knockdown, pharmacological PKG activation (GSNO/cGMP), co-IP for MPRIP-MYPT1 association, phospho-MLC quantification in permeabilized cells","journal":"Cell biochemistry and biophysics","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical co-IP combined with siRNA rescue and phosphorylation assays, single lab","pmids":["23723008"],"is_preprint":false},{"year":2019,"finding":"MPRIP (p116Rip) knockdown in human airway smooth muscle cells increases di-phosphorylated MLC (Ser19 and Thr18) by altering the interaction between MLCP and myosin rather than changing RhoA/ROCK signaling. ZIPK is involved in this increased di-phosphorylation. MPRIP suppression also increases histamine-induced collagen gel contraction.","method":"siRNA knockdown, phospho-MLC quantification, ROCK activity assay, co-IP of MLCP-myosin, ZIPK inhibitor, collagen gel contraction assay","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple biochemical and functional readouts, single lab","pmids":["31347175"],"is_preprint":false},{"year":2020,"finding":"Ermin associates with MPRIP (p116Rip) and together they inactivate RhoA to promote oligodendrocyte morphogenesis and differentiation. Loss of Ermin in knockout mice results in aberrant myelin architecture, accelerated demyelination, and motor coordination deficits.","method":"Co-IP (Ermin-MPRIP interaction), Ermn knockout mouse, RhoA activity assay, behavioral and histological analysis","journal":"Glia","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO combined with co-IP and GTPase assay, single lab","pmids":["32530539"],"is_preprint":false},{"year":2021,"finding":"MPRIP is present in the cell nucleus where it binds phosphatidylinositol 4,5-bisphosphate (PIP2), localizes to nuclear speckles and nuclear lipid islets, associates with the RNA Polymerase II/Nuclear Myosin 1 complex, and forms phase-separated condensates that bind nuclear F-actin fibers. Phase separation is driven by its long intrinsically disordered C-terminal region.","method":"Subcellular fractionation, confocal and super-resolution microscopy, co-IP/mass spectrometry, PIP2 binding assay, live-cell imaging of condensate dynamics, deletion mutant analysis","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods for nuclear localization and phase separation, single lab","pmids":["33918018"],"is_preprint":false},{"year":2023,"finding":"Nuclear MPRIP recruits Tyr1-phosphorylated CTD of RNAPII to nuclear PIP2-containing structures via its N-terminal F-actin-binding domain. MPRIP depletion increases the number of RNAPII initiation condensates, indicating a defect in transcription elongation/pause-release. MPRIP regulates RNAPII condensation and transcription through PIP2-rich nuclear structures.","method":"siRNA depletion, super-resolution microscopy, co-IP, proximity ligation assay, transcription assays","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 — multiple microscopy and biochemical approaches in single lab","pmids":["36979361"],"is_preprint":false},{"year":2023,"finding":"LRRC8A volume-regulated anion channels physically associate with MPRIP at the second Pleckstrin Homology domain of MPRIP in vascular smooth muscle cells. MPRIP links LRRC8A/Nox1 to the RhoA/MYPT1/actin cytoskeletal regulation pathway and is a target of redox modification (sulfenylation) following TNFα exposure.","method":"Immunoprecipitation/mass spectrometry, confocal co-localization, proximity ligation assay, IP/western blot with domain mapping, siRNA, redox proteomics","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal interaction assays with domain mapping, preprint","pmids":["36945623"],"is_preprint":true},{"year":2025,"finding":"During apoptosis, MPRIP is cleaved by caspases to generate a C-terminal fragment that retains interaction with MYPT1. This fragment translocates to the cytoplasm and forms a complex with MYPT1 and myosin, promoting dephosphorylation of regulatory myosin light chain (RMLC) at retracting blebs, thereby regulating the phosphorylation/dephosphorylation cycle that drives repetitive bleb formation.","method":"FRET-based RMLC phosphorylation biosensor, 3D live imaging, in vitro caspase cleavage assay, co-IP of cleaved fragment with MYPT1/myosin, mutant/domain analysis","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro caspase assay plus FRET biosensor plus co-IP with domain analysis, multiple orthogonal methods in single study","pmids":["40344468"],"is_preprint":false}],"current_model":"MPRIP (p116Rip/M-RIP) is a scaffold protein that binds F-actin (and bundles it in vitro), directly interacts with the myosin phosphatase targeting subunit MYPT1 and with RhoA, thereby targeting myosin light chain phosphatase to actomyosin stress fibers to promote myosin dephosphorylation and relaxation; it additionally acts as a RhoA GAP-like regulator, is phosphorylated by PKG to enhance MLCP activity, is cleaved by caspases during apoptosis to generate a MYPT1-binding fragment that regulates bleb formation, and functions in the nucleus as a PIP2-binding, phase-separating regulator of RNA Polymerase II transcription via nuclear F-actin and condensate dynamics."},"narrative":{"teleology":[{"year":2003,"claim":"Establishing that MPRIP is an F-actin-binding and bundling protein that co-localizes with stress fibers and myosin-II answered the fundamental question of how MPRIP interfaces with the actomyosin cytoskeleton.","evidence":"F-actin co-sedimentation (Kd ~0.5 µM), electron microscopy of bundles, immunoprecipitation, and deletion-mutant imaging in cultured cells","pmids":["12732640"],"confidence":"High","gaps":["Structural basis of actin binding and bundling not resolved","Whether bundling activity is physiologically relevant in vivo was untested"]},{"year":2004,"claim":"Demonstrating that MPRIP directly binds MYPT1, activates MLCP toward myosin substrates, and functions as a RhoA GAP-like regulator established the dual mechanism by which MPRIP promotes myosin dephosphorylation — enhancing phosphatase targeting and reducing upstream RhoA signaling.","evidence":"In vitro GTPase and phosphatase assays, domain-mapping co-IP, siRNA knockdown with phospho-MLC quantification in multiple cell types","pmids":["15545284","15469989"],"confidence":"High","gaps":["Whether GAP activity and MLCP-targeting function independently or cooperatively in vivo was unresolved","Identity of residues mediating RhoA GAP activity not defined"]},{"year":2005,"claim":"Showing that MPRIP targets MYPT1 to stress fibers in vascular smooth muscle cells, with its loss increasing basal myosin phosphorylation and stress fiber density, confirmed the physiological scaffolding function in a contractile cell type relevant to vascular tone.","evidence":"siRNA knockdown in vascular smooth muscle cells with immunofluorescence localization and phospho-MLC quantification","pmids":["16257966"],"confidence":"High","gaps":["In vivo relevance in intact vasculature or animal models not tested","Regulation of MPRIP expression or stability in smooth muscle was unknown"]},{"year":2012,"claim":"Identifying the MPRIP–syntenin-1 complex as a Src-dependent hub for polarized Rac-1 activation extended MPRIP's role beyond myosin phosphatase targeting to spatially regulated actin polymerization at the leading edge and immune synapse.","evidence":"Co-IP with phospho-mutants, siRNA knockdown, GTPase activity assays, and confocal imaging in T cells","pmids":["22349701"],"confidence":"Medium","gaps":["Whether MPRIP's Rac-1 regulatory role is independent of its MLCP-targeting function was not dissected","Single lab finding not independently confirmed"]},{"year":2014,"claim":"Demonstrating PKG-mediated phosphorylation of MPRIP as a mechanism to enhance MPRIP–MYPT1 association and MLCP activity established how the cGMP/NO signaling axis converges on MPRIP to promote smooth muscle relaxation.","evidence":"PKG activation (GSNO/cGMP) with co-IP for MPRIP–MYPT1 binding, siRNA rescue, and phospho-MLC quantification in gastric smooth muscle","pmids":["23723008"],"confidence":"Medium","gaps":["Specific PKG phosphorylation site(s) on MPRIP not mapped","Whether PKG phosphorylation also affects RhoA GAP activity was not tested"]},{"year":2019,"claim":"Revealing that MPRIP depletion in airway smooth muscle increases di-phosphorylated MLC via impaired MLCP–myosin interaction (with ZIPK involvement) extended the scaffolding model to airway contractility and identified a previously unrecognized kinase input.","evidence":"siRNA knockdown, phospho-MLC quantification, co-IP of MLCP–myosin, ZIPK inhibitor, collagen gel contraction assay in human airway smooth muscle cells","pmids":["31347175"],"confidence":"Medium","gaps":["Mechanism by which ZIPK compensates for MPRIP loss is unclear","In vivo airway contractility data not provided"]},{"year":2020,"claim":"Identifying Ermin as an MPRIP partner that cooperates to inactivate RhoA for oligodendrocyte morphogenesis connected MPRIP's cytoskeletal regulatory function to CNS myelination.","evidence":"Co-IP, RhoA activity assay, Ermn knockout mouse with histological, behavioral, and myelin analysis","pmids":["32530539"],"confidence":"Medium","gaps":["Direct loss of MPRIP in oligodendrocytes or CNS was not tested","Whether MPRIP's GAP-like activity or MLCP-targeting underlies the myelination phenotype is undetermined"]},{"year":2021,"claim":"Discovering that MPRIP localizes to the nucleus, binds PIP2, associates with RNAPII/Nuclear Myosin 1, and forms phase-separated condensates via its intrinsically disordered region revealed an unexpected nuclear function beyond cytoskeletal regulation.","evidence":"Subcellular fractionation, super-resolution microscopy, co-IP/mass spectrometry, PIP2 binding assay, live-cell condensate imaging, deletion mutant analysis","pmids":["33918018"],"confidence":"Medium","gaps":["Functional consequence of nuclear condensates for gene expression not established","Mechanism separating cytoplasmic versus nuclear pools of MPRIP unknown"]},{"year":2023,"claim":"Showing that nuclear MPRIP recruits elongating (Tyr1-phosphorylated) RNAPII to PIP2 structures, and that its depletion increases RNAPII initiation condensates, established MPRIP as a regulator of transcription elongation/pause-release through nuclear lipid–actin compartments.","evidence":"siRNA depletion, super-resolution microscopy, co-IP, proximity ligation assay, transcription assays","pmids":["36979361"],"confidence":"Medium","gaps":["Genome-wide transcriptional targets affected by MPRIP loss not identified","Whether F-actin binding and PIP2 binding are independently required for transcription regulation is unresolved","Single lab findings require independent confirmation"]},{"year":2025,"claim":"Demonstrating that caspase cleavage of MPRIP generates a C-terminal fragment that retains MYPT1 binding and promotes localized MLC dephosphorylation at retracting blebs established how apoptotic cells repurpose the MPRIP–MLCP axis for dynamic bleb regulation.","evidence":"In vitro caspase cleavage assay, FRET-based RMLC phosphorylation biosensor, 3D live imaging, co-IP of cleaved fragment with MYPT1/myosin, domain analysis","pmids":["40344468"],"confidence":"High","gaps":["Specific caspase(s) responsible for cleavage in vivo not definitively identified","Whether caspase cleavage also affects nuclear MPRIP functions is unexplored"]},{"year":null,"claim":"How MPRIP's cytoplasmic scaffolding of MLCP and its nuclear phase-separation/transcription functions are coordinated, regulated by signaling cues, and partitioned between compartments remains an open question.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of MPRIP or its complexes exists","No MPRIP knockout animal model has been characterized","Mechanism governing nuclear–cytoplasmic partitioning of MPRIP is unknown","Genome-wide transcriptional consequences of MPRIP loss are undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2,3,7,8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,4,9]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[10,11]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,1,13]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[10,11]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[10,11]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,7,9]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[13]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[10,11]},{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[3,7,8]}],"complexes":["Myosin phosphatase (MLCP/MYPT1) complex","RNAPII/Nuclear Myosin 1 complex"],"partners":["MYPT1","RHOA","SDCBP","ERMN","LRRC8A","MYH9","NM1"],"other_free_text":[]},"mechanistic_narrative":"MPRIP is a multifunctional scaffold protein that spatially targets myosin light chain phosphatase (MLCP) to actomyosin stress fibers, thereby controlling myosin II phosphorylation, contractility, and cytoskeletal dynamics across diverse cell types. Its N-terminal region binds and bundles F-actin (Kd ~0.5 µM), while its C-terminal coiled-coil domain binds the myosin phosphatase targeting subunit MYPT1 and mediates oligomerization; loss of MPRIP displaces MYPT1 from stress fibers and increases myosin light chain phosphorylation, augmenting contractility [PMID:12732640, PMID:16257966, PMID:31347175]. MPRIP additionally inactivates RhoA through a GAP-like activity, is phosphorylated by PKG to enhance MLCP function, and is cleaved by caspases during apoptosis to generate a MYPT1-binding fragment that regulates bleb retraction through localized myosin dephosphorylation [PMID:15545284, PMID:23723008, PMID:40344468]. In the nucleus, MPRIP binds PIP2, forms phase-separated condensates via its intrinsically disordered region, and recruits Tyr1-phosphorylated RNA Polymerase II to PIP2-containing structures, regulating transcription elongation and RNAPII condensate dynamics [PMID:33918018, PMID:36979361]."},"prefetch_data":{"uniprot":{"accession":"Q6WCQ1","full_name":"Myosin phosphatase Rho-interacting protein","aliases":["Rho-interacting protein 3","RIP3","p116Rip"],"length_aa":1025,"mass_kda":116.5,"function":"Targets myosin phosphatase to the actin cytoskeleton. Required for the regulation of the actin cytoskeleton by RhoA and ROCK1. Depletion leads to an increased number of stress fibers in smooth muscle cells through stabilization of actin fibers by phosphorylated myosin. Overexpression of MRIP as well as its F-actin-binding region leads to disassembly of stress fibers in neuronal cells","subcellular_location":"Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/Q6WCQ1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MPRIP","classification":"Not Classified","n_dependent_lines":120,"n_total_lines":1208,"dependency_fraction":0.09933774834437085},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALD1","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"CTTN","stoichiometry":0.2},{"gene":"PACSIN2","stoichiometry":0.2},{"gene":"PACSIN3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MPRIP","total_profiled":1310},"omim":[{"mim_id":"614071","title":"MYOCARDIAL ZONULA ADHERENS PROTEIN; MYZAP","url":"https://www.omim.org/entry/614071"},{"mim_id":"612935","title":"MYOSIN PHOSPHATASE RHO-INTERACTING PROTEIN; MPRIP","url":"https://www.omim.org/entry/612935"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Actin filaments","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MPRIP"},"hgnc":{"alias_symbol":["RHOIP3","M-RIP","p116Rip"],"prev_symbol":[]},"alphafold":{"accession":"Q6WCQ1","domains":[{"cath_id":"2.30.29.30","chopping":"43-158","consensus_level":"high","plddt":87.917,"start":43,"end":158},{"cath_id":"2.30.29.30","chopping":"392-483","consensus_level":"high","plddt":86.7948,"start":392,"end":483},{"cath_id":"1.20.5","chopping":"721-804","consensus_level":"medium","plddt":95.2381,"start":721,"end":804}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6WCQ1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6WCQ1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6WCQ1-F1-predicted_aligned_error_v6.png","plddt_mean":64.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MPRIP","jax_strain_url":"https://www.jax.org/strain/search?query=MPRIP"},"sequence":{"accession":"Q6WCQ1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6WCQ1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6WCQ1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6WCQ1"}},"corpus_meta":[{"pmid":"15545284","id":"PMC_15545284","title":"p116Rip decreases myosin II phosphorylation by activating myosin light chain phosphatase and by inactivating RhoA.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15545284","citation_count":57,"is_preprint":false},{"pmid":"16257966","id":"PMC_16257966","title":"M-RIP targets myosin phosphatase to stress fibers to regulate myosin light chain phosphorylation in vascular smooth muscle cells.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16257966","citation_count":55,"is_preprint":false},{"pmid":"15469989","id":"PMC_15469989","title":"p116Rip targets myosin phosphatase to the actin cytoskeleton and is essential for RhoA/ROCK-regulated neuritogenesis.","date":"2004","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/15469989","citation_count":39,"is_preprint":false},{"pmid":"12732640","id":"PMC_12732640","title":"p116Rip is a novel filamentous actin-binding protein.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12732640","citation_count":31,"is_preprint":false},{"pmid":"22349701","id":"PMC_22349701","title":"Association of syntenin-1 with M-RIP polarizes Rac-1 activation during chemotaxis and immune interactions.","date":"2012","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/22349701","citation_count":31,"is_preprint":false},{"pmid":"26355392","id":"PMC_26355392","title":"Fusion of PDGFRB to MPRIP, CPSF6, and GOLGB1 in three patients with eosinophilia-associated myeloproliferative neoplasms.","date":"2015","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/26355392","citation_count":28,"is_preprint":false},{"pmid":"33918018","id":"PMC_33918018","title":"The F-Actin-Binding MPRIP Forms Phase-Separated Condensates and Associates with PI(4,5)P2 and Active RNA Polymerase II in the Cell Nucleus.","date":"2021","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/33918018","citation_count":24,"is_preprint":false},{"pmid":"36979361","id":"PMC_36979361","title":"PIP2-Effector Protein MPRIP Regulates RNA Polymerase II Condensation and Transcription.","date":"2023","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/36979361","citation_count":16,"is_preprint":false},{"pmid":"32530539","id":"PMC_32530539","title":"Ermin is a p116RIP -interacting protein promoting oligodendroglial differentiation and myelin maintenance.","date":"2020","source":"Glia","url":"https://pubmed.ncbi.nlm.nih.gov/32530539","citation_count":16,"is_preprint":false},{"pmid":"16243315","id":"PMC_16243315","title":"Inhibition of RhoA-mediated SRF activation by p116Rip.","date":"2005","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/16243315","citation_count":13,"is_preprint":false},{"pmid":"18636174","id":"PMC_18636174","title":"M-RIP, a novel target of JNK signaling and a requirement for human cancer cell invasion.","date":"2008","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/18636174","citation_count":13,"is_preprint":false},{"pmid":"23723008","id":"PMC_23723008","title":"Inhibition of MLC20 phosphorylation downstream of Ca2+ and RhoA: A novel mechanism involving phosphorylation of myosin phosphatase interacting protein (M-RIP) by PKG and stimulation of MLC phosphatase activity.","date":"2014","source":"Cell biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/23723008","citation_count":12,"is_preprint":false},{"pmid":"31347175","id":"PMC_31347175","title":"p116Rip promotes myosin phosphatase activity in airway smooth muscle cells.","date":"2019","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/31347175","citation_count":8,"is_preprint":false},{"pmid":"33116618","id":"PMC_33116618","title":"Identification of a Novel MPRIP-ROS1 Fusion and Clinical Efficacy of Crizotinib in an Advanced Lung Adenocarcinoma Patient: A Case Report.","date":"2020","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/33116618","citation_count":7,"is_preprint":false},{"pmid":"36813871","id":"PMC_36813871","title":"Germline VWF/MPRIP and somatoplasm FGA variants synergically confer susceptibility to non-traumatic osteonecrosis of the femoral head.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36813871","citation_count":2,"is_preprint":false},{"pmid":"36945623","id":"PMC_36945623","title":"LRRC8A anion channels modulate vasodilation via association with Myosin Phosphatase Rho Interacting Protein (MPRIP).","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/36945623","citation_count":2,"is_preprint":false},{"pmid":"40344468","id":"PMC_40344468","title":"Caspase-mediated cleavage of a scaffold protein, MPRIP, yields a truncated form that is involved in repetitive bleb formation.","date":"2025","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/40344468","citation_count":0,"is_preprint":false},{"pmid":"40678598","id":"PMC_40678598","title":"Remarkable response to crizotinib in a patient with advanced lung adenocarcinoma harboring the MPRIP-ROS1 fusion gene: A case report.","date":"2025","source":"Respiratory medicine case reports","url":"https://pubmed.ncbi.nlm.nih.gov/40678598","citation_count":0,"is_preprint":false},{"pmid":"40621131","id":"PMC_40621131","title":"MPRIP::PDGFRB Fusion Gene: A Rare Case Report of Adult Myeloid/Lymphoid Neoplasm With Eosinophilia and Tyrosine Kinase Gene Fusions.","date":"2025","source":"Case reports in hematology","url":"https://pubmed.ncbi.nlm.nih.gov/40621131","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10515,"output_tokens":3624,"usd":0.042952},"stage2":{"model":"claude-opus-4-6","input_tokens":7012,"output_tokens":3132,"usd":0.17004},"total_usd":0.212992,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"MPRIP (p116Rip) is a filamentous actin-binding protein that localizes to F-actin-rich structures (stress fibers, cortical microfilaments) via its N-terminal region (residues 1-382), binds F-actin with Kd ~0.5 µM, bundles F-actin in vitro, and is complexed with both F-actin and myosin-II in cells. Overexpression disrupts stress fibers and inhibits growth factor-induced lamellipodia formation.\",\n      \"method\": \"F-actin co-sedimentation, immunoprecipitation, electron microscopy of F-actin bundles, live/fixed cell imaging with deletion mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (biochemical binding assay, EM, IP, cell imaging with domain mutants) in a single study\",\n      \"pmids\": [\"12732640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"MPRIP (p116Rip) activates the GTPase activity of RhoA in vitro (acting as a GAP-like regulator) and reduces GTP-bound RhoA levels in cells after EGF stimulation. It also activates myosin light chain phosphatase (MLCP) holoenzyme activity specifically toward myosin as substrate by binding the myosin phosphatase targeting subunit MYPT1 and directly binding myosin, thereby facilitating myosin/MLCP interaction. Gene silencing of p116Rip increases myosin phosphorylation and stress fiber formation.\",\n      \"method\": \"In vitro GTPase assay, RhoA-GTP pulldown in cells, in vitro phosphatase activity assay, siRNA knockdown with phospho-MLC immunostaining\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro biochemical assays combined with cell-based siRNA knockdown and multiple readouts, single rigorous study\",\n      \"pmids\": [\"15545284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"MPRIP (p116Rip) interacts directly with the C-terminal leucine zipper of the regulatory myosin-binding subunits of myosin II phosphatase (MBS85 and MBS130) via its C-terminal coiled-coil domain, and targets the myosin phosphatase complex to the actin cytoskeleton. RNAi-mediated knockdown of p116Rip inhibits cell spreading and neurite outgrowth in response to extracellular cues without altering myosin light chain phosphorylation.\",\n      \"method\": \"Direct protein interaction assays (co-IP, domain mapping), RNAi knockdown with morphological readouts (cell spreading, neurite outgrowth)\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal interaction assays with domain mutants plus RNAi phenotype, replicated binding finding from other labs\",\n      \"pmids\": [\"15469989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MPRIP (M-RIP) targets myosin phosphatase (via its myosin binding subunit MYPT1) to actin-myosin stress fibers in vascular smooth muscle cells. RNAi silencing of M-RIP reduced stress fiber localization of MYPT1, increased basal and LPA-stimulated myosin light chain phosphorylation, increased stress fiber numbers and cell area, and reduced stress fiber inhibition by a Rho-kinase inhibitor, without changing total cellular myosin phosphatase, MLCK, or RhoA activities.\",\n      \"method\": \"siRNA knockdown, immunofluorescence localization, phospho-MLC quantification, Rho-kinase inhibitor functional assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean siRNA with multiple orthogonal cellular readouts, consistent with parallel studies in other cell types\",\n      \"pmids\": [\"16257966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MPRIP (p116Rip) oligomerizes via its C-terminal coiled-coil domain and inhibits RhoA-induced SRF transcriptional activation by disassembling the actomyosin cytoskeleton downstream of RhoA, independently of effects on RhoA-GTP levels. Mutant forms unable to oligomerize or bind MBS still inhibit SRF activity.\",\n      \"method\": \"Overexpression with SRF reporter assay, domain mutant analysis, RhoA-GTP pulldown\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, overexpression system with reporter assay and mutants but no in vitro reconstitution\",\n      \"pmids\": [\"16243315\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MPRIP (M-RIP) expression is induced downstream of JNK1 signaling in response to EGF, and siRNA-mediated knockdown of M-RIP significantly reduces the invasive activity of HeLa cancer cells.\",\n      \"method\": \"siRNA knockdown, microarray gene expression, Matrigel invasion assay\",\n      \"journal\": \"International journal of molecular medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, single method for invasion phenotype, pathway placement based on expression change only\",\n      \"pmids\": [\"18636174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"MPRIP (M-RIP) associates with the PDZ protein syntenin-1 in a manner dependent on Src-mediated phosphorylation of syntenin-1 at Tyr4. This MPRIP-syntenin-1 complex is required for polarized Rac-1 activation and actin polymerization at the leading edge and immune synapse during T cell chemotaxis and APC interactions.\",\n      \"method\": \"Co-IP, mutant analysis, siRNA knockdown, GTPase activity assays, confocal microscopy of actin polarization\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — co-IP with phospho-mutants and siRNA phenotype, single lab\",\n      \"pmids\": [\"22349701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PKG phosphorylates MPRIP (M-RIP), which enhances the association of MPRIP with MYPT1 and increases MLCP activity, leading to MLC20 dephosphorylation and muscle relaxation in gastric smooth muscle cells, operating downstream of both Ca2+- and RhoA-dependent pathways.\",\n      \"method\": \"siRNA knockdown, pharmacological PKG activation (GSNO/cGMP), co-IP for MPRIP-MYPT1 association, phospho-MLC quantification in permeabilized cells\",\n      \"journal\": \"Cell biochemistry and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical co-IP combined with siRNA rescue and phosphorylation assays, single lab\",\n      \"pmids\": [\"23723008\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MPRIP (p116Rip) knockdown in human airway smooth muscle cells increases di-phosphorylated MLC (Ser19 and Thr18) by altering the interaction between MLCP and myosin rather than changing RhoA/ROCK signaling. ZIPK is involved in this increased di-phosphorylation. MPRIP suppression also increases histamine-induced collagen gel contraction.\",\n      \"method\": \"siRNA knockdown, phospho-MLC quantification, ROCK activity assay, co-IP of MLCP-myosin, ZIPK inhibitor, collagen gel contraction assay\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple biochemical and functional readouts, single lab\",\n      \"pmids\": [\"31347175\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Ermin associates with MPRIP (p116Rip) and together they inactivate RhoA to promote oligodendrocyte morphogenesis and differentiation. Loss of Ermin in knockout mice results in aberrant myelin architecture, accelerated demyelination, and motor coordination deficits.\",\n      \"method\": \"Co-IP (Ermin-MPRIP interaction), Ermn knockout mouse, RhoA activity assay, behavioral and histological analysis\",\n      \"journal\": \"Glia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO combined with co-IP and GTPase assay, single lab\",\n      \"pmids\": [\"32530539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MPRIP is present in the cell nucleus where it binds phosphatidylinositol 4,5-bisphosphate (PIP2), localizes to nuclear speckles and nuclear lipid islets, associates with the RNA Polymerase II/Nuclear Myosin 1 complex, and forms phase-separated condensates that bind nuclear F-actin fibers. Phase separation is driven by its long intrinsically disordered C-terminal region.\",\n      \"method\": \"Subcellular fractionation, confocal and super-resolution microscopy, co-IP/mass spectrometry, PIP2 binding assay, live-cell imaging of condensate dynamics, deletion mutant analysis\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods for nuclear localization and phase separation, single lab\",\n      \"pmids\": [\"33918018\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Nuclear MPRIP recruits Tyr1-phosphorylated CTD of RNAPII to nuclear PIP2-containing structures via its N-terminal F-actin-binding domain. MPRIP depletion increases the number of RNAPII initiation condensates, indicating a defect in transcription elongation/pause-release. MPRIP regulates RNAPII condensation and transcription through PIP2-rich nuclear structures.\",\n      \"method\": \"siRNA depletion, super-resolution microscopy, co-IP, proximity ligation assay, transcription assays\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple microscopy and biochemical approaches in single lab\",\n      \"pmids\": [\"36979361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LRRC8A volume-regulated anion channels physically associate with MPRIP at the second Pleckstrin Homology domain of MPRIP in vascular smooth muscle cells. MPRIP links LRRC8A/Nox1 to the RhoA/MYPT1/actin cytoskeletal regulation pathway and is a target of redox modification (sulfenylation) following TNFα exposure.\",\n      \"method\": \"Immunoprecipitation/mass spectrometry, confocal co-localization, proximity ligation assay, IP/western blot with domain mapping, siRNA, redox proteomics\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal interaction assays with domain mapping, preprint\",\n      \"pmids\": [\"36945623\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"During apoptosis, MPRIP is cleaved by caspases to generate a C-terminal fragment that retains interaction with MYPT1. This fragment translocates to the cytoplasm and forms a complex with MYPT1 and myosin, promoting dephosphorylation of regulatory myosin light chain (RMLC) at retracting blebs, thereby regulating the phosphorylation/dephosphorylation cycle that drives repetitive bleb formation.\",\n      \"method\": \"FRET-based RMLC phosphorylation biosensor, 3D live imaging, in vitro caspase cleavage assay, co-IP of cleaved fragment with MYPT1/myosin, mutant/domain analysis\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro caspase assay plus FRET biosensor plus co-IP with domain analysis, multiple orthogonal methods in single study\",\n      \"pmids\": [\"40344468\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MPRIP (p116Rip/M-RIP) is a scaffold protein that binds F-actin (and bundles it in vitro), directly interacts with the myosin phosphatase targeting subunit MYPT1 and with RhoA, thereby targeting myosin light chain phosphatase to actomyosin stress fibers to promote myosin dephosphorylation and relaxation; it additionally acts as a RhoA GAP-like regulator, is phosphorylated by PKG to enhance MLCP activity, is cleaved by caspases during apoptosis to generate a MYPT1-binding fragment that regulates bleb formation, and functions in the nucleus as a PIP2-binding, phase-separating regulator of RNA Polymerase II transcription via nuclear F-actin and condensate dynamics.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MPRIP is a multifunctional scaffold protein that spatially targets myosin light chain phosphatase (MLCP) to actomyosin stress fibers, thereby controlling myosin II phosphorylation, contractility, and cytoskeletal dynamics across diverse cell types. Its N-terminal region binds and bundles F-actin (Kd ~0.5 µM), while its C-terminal coiled-coil domain binds the myosin phosphatase targeting subunit MYPT1 and mediates oligomerization; loss of MPRIP displaces MYPT1 from stress fibers and increases myosin light chain phosphorylation, augmenting contractility [PMID:12732640, PMID:16257966, PMID:31347175]. MPRIP additionally inactivates RhoA through a GAP-like activity, is phosphorylated by PKG to enhance MLCP function, and is cleaved by caspases during apoptosis to generate a MYPT1-binding fragment that regulates bleb retraction through localized myosin dephosphorylation [PMID:15545284, PMID:23723008, PMID:40344468]. In the nucleus, MPRIP binds PIP2, forms phase-separated condensates via its intrinsically disordered region, and recruits Tyr1-phosphorylated RNA Polymerase II to PIP2-containing structures, regulating transcription elongation and RNAPII condensate dynamics [PMID:33918018, PMID:36979361].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing that MPRIP is an F-actin-binding and bundling protein that co-localizes with stress fibers and myosin-II answered the fundamental question of how MPRIP interfaces with the actomyosin cytoskeleton.\",\n      \"evidence\": \"F-actin co-sedimentation (Kd ~0.5 µM), electron microscopy of bundles, immunoprecipitation, and deletion-mutant imaging in cultured cells\",\n      \"pmids\": [\"12732640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of actin binding and bundling not resolved\",\n        \"Whether bundling activity is physiologically relevant in vivo was untested\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrating that MPRIP directly binds MYPT1, activates MLCP toward myosin substrates, and functions as a RhoA GAP-like regulator established the dual mechanism by which MPRIP promotes myosin dephosphorylation — enhancing phosphatase targeting and reducing upstream RhoA signaling.\",\n      \"evidence\": \"In vitro GTPase and phosphatase assays, domain-mapping co-IP, siRNA knockdown with phospho-MLC quantification in multiple cell types\",\n      \"pmids\": [\"15545284\", \"15469989\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether GAP activity and MLCP-targeting function independently or cooperatively in vivo was unresolved\",\n        \"Identity of residues mediating RhoA GAP activity not defined\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showing that MPRIP targets MYPT1 to stress fibers in vascular smooth muscle cells, with its loss increasing basal myosin phosphorylation and stress fiber density, confirmed the physiological scaffolding function in a contractile cell type relevant to vascular tone.\",\n      \"evidence\": \"siRNA knockdown in vascular smooth muscle cells with immunofluorescence localization and phospho-MLC quantification\",\n      \"pmids\": [\"16257966\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo relevance in intact vasculature or animal models not tested\",\n        \"Regulation of MPRIP expression or stability in smooth muscle was unknown\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying the MPRIP–syntenin-1 complex as a Src-dependent hub for polarized Rac-1 activation extended MPRIP's role beyond myosin phosphatase targeting to spatially regulated actin polymerization at the leading edge and immune synapse.\",\n      \"evidence\": \"Co-IP with phospho-mutants, siRNA knockdown, GTPase activity assays, and confocal imaging in T cells\",\n      \"pmids\": [\"22349701\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether MPRIP's Rac-1 regulatory role is independent of its MLCP-targeting function was not dissected\",\n        \"Single lab finding not independently confirmed\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating PKG-mediated phosphorylation of MPRIP as a mechanism to enhance MPRIP–MYPT1 association and MLCP activity established how the cGMP/NO signaling axis converges on MPRIP to promote smooth muscle relaxation.\",\n      \"evidence\": \"PKG activation (GSNO/cGMP) with co-IP for MPRIP–MYPT1 binding, siRNA rescue, and phospho-MLC quantification in gastric smooth muscle\",\n      \"pmids\": [\"23723008\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific PKG phosphorylation site(s) on MPRIP not mapped\",\n        \"Whether PKG phosphorylation also affects RhoA GAP activity was not tested\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealing that MPRIP depletion in airway smooth muscle increases di-phosphorylated MLC via impaired MLCP–myosin interaction (with ZIPK involvement) extended the scaffolding model to airway contractility and identified a previously unrecognized kinase input.\",\n      \"evidence\": \"siRNA knockdown, phospho-MLC quantification, co-IP of MLCP–myosin, ZIPK inhibitor, collagen gel contraction assay in human airway smooth muscle cells\",\n      \"pmids\": [\"31347175\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which ZIPK compensates for MPRIP loss is unclear\",\n        \"In vivo airway contractility data not provided\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identifying Ermin as an MPRIP partner that cooperates to inactivate RhoA for oligodendrocyte morphogenesis connected MPRIP's cytoskeletal regulatory function to CNS myelination.\",\n      \"evidence\": \"Co-IP, RhoA activity assay, Ermn knockout mouse with histological, behavioral, and myelin analysis\",\n      \"pmids\": [\"32530539\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct loss of MPRIP in oligodendrocytes or CNS was not tested\",\n        \"Whether MPRIP's GAP-like activity or MLCP-targeting underlies the myelination phenotype is undetermined\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Discovering that MPRIP localizes to the nucleus, binds PIP2, associates with RNAPII/Nuclear Myosin 1, and forms phase-separated condensates via its intrinsically disordered region revealed an unexpected nuclear function beyond cytoskeletal regulation.\",\n      \"evidence\": \"Subcellular fractionation, super-resolution microscopy, co-IP/mass spectrometry, PIP2 binding assay, live-cell condensate imaging, deletion mutant analysis\",\n      \"pmids\": [\"33918018\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of nuclear condensates for gene expression not established\",\n        \"Mechanism separating cytoplasmic versus nuclear pools of MPRIP unknown\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showing that nuclear MPRIP recruits elongating (Tyr1-phosphorylated) RNAPII to PIP2 structures, and that its depletion increases RNAPII initiation condensates, established MPRIP as a regulator of transcription elongation/pause-release through nuclear lipid–actin compartments.\",\n      \"evidence\": \"siRNA depletion, super-resolution microscopy, co-IP, proximity ligation assay, transcription assays\",\n      \"pmids\": [\"36979361\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Genome-wide transcriptional targets affected by MPRIP loss not identified\",\n        \"Whether F-actin binding and PIP2 binding are independently required for transcription regulation is unresolved\",\n        \"Single lab findings require independent confirmation\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrating that caspase cleavage of MPRIP generates a C-terminal fragment that retains MYPT1 binding and promotes localized MLC dephosphorylation at retracting blebs established how apoptotic cells repurpose the MPRIP–MLCP axis for dynamic bleb regulation.\",\n      \"evidence\": \"In vitro caspase cleavage assay, FRET-based RMLC phosphorylation biosensor, 3D live imaging, co-IP of cleaved fragment with MYPT1/myosin, domain analysis\",\n      \"pmids\": [\"40344468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Specific caspase(s) responsible for cleavage in vivo not definitively identified\",\n        \"Whether caspase cleavage also affects nuclear MPRIP functions is unexplored\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MPRIP's cytoplasmic scaffolding of MLCP and its nuclear phase-separation/transcription functions are coordinated, regulated by signaling cues, and partitioned between compartments remains an open question.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of MPRIP or its complexes exists\",\n        \"No MPRIP knockout animal model has been characterized\",\n        \"Mechanism governing nuclear–cytoplasmic partitioning of MPRIP is unknown\",\n        \"Genome-wide transcriptional consequences of MPRIP loss are undefined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2, 3, 7, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 4, 9]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [10, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 1, 13]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10, 11]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [10, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 7, 9]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [10, 11]},\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [3, 7, 8]}\n    ],\n    \"complexes\": [\n      \"Myosin phosphatase (MLCP/MYPT1) complex\",\n      \"RNAPII/Nuclear Myosin 1 complex\"\n    ],\n    \"partners\": [\n      \"MYPT1\",\n      \"RHOA\",\n      \"SDCBP\",\n      \"ERMN\",\n      \"LRRC8A\",\n      \"MYH9\",\n      \"NM1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}