Affinage

SRGAP1

SLIT-ROBO Rho GTPase-activating protein 1 · UniProt Q7Z6B7

Length
1085 aa
Mass
124.3 kDa
Annotated
2026-04-28
16 papers in source corpus 14 papers cited in narrative 14 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SRGAP1 is a multi-domain RhoGAP protein that couples Slit-Robo guidance signaling to the spatiotemporal control of Rho-family GTPase activity, thereby regulating cell migration, membrane dynamics, and cell-cell junction contractility. Its SH3 domain binds proline-rich CC2/CC3 motifs of Robo1 in a structurally defined C-to-N orientation (PMID:16857672), and upon Slit2 stimulation it inactivates Cdc42 to suppress immune cell chemotaxis and neuroinflammation (PMID:20944010, PMID:37899442), or acts as a Rac1-specific GAP to limit lamellipodial protrusion and enable concomitant RhoA activation for balanced cell motility (PMID:24006490). At epithelial adherens junctions, tyrosine-dephosphorylated cortactin recruits SRGAP1 to antagonize RhoA and reduce junctional contractility, a mechanism co-opted by HGF for collective cell motility (PMID:28983097, PMID:29160905). In podocytes, SRGAP1 localizes to foot processes and restrains Rho GTPase-driven protrusion; its conditional deletion causes FSGS-like foot-process effacement, and disease-associated missense mutations in its F-BAR and RhoGAP domains impair GTPase inactivation (PMID:33514561, PMID:23539728).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2006 High

    Determining how SRGAP1 physically engages the Robo receptor: the crystal structure of the SH3 domain revealed it binds Robo1 CC2/CC3 proline-rich motifs in a defined C-to-N orientation, establishing the structural basis for Slit-Robo-to-GAP coupling.

    Evidence 1.8 Å X-ray crystal structure, surface plasmon resonance, peptide mutagenesis

    PMID:16857672

    Open questions at the time
    • No full-length SRGAP1 structure; how F-BAR and GAP domains coordinate with the SH3 domain during Robo binding is unknown
    • Affinity measurements for endogenous Robo1 in cellular contexts not provided
  2. 2010 Medium

    Demonstrating functional relevance of the Robo1-srGAP1 axis in immune cells: Slit2 activates srGAP1 to inactivate Cdc42 and suppress neutrophil chemotaxis, while low srGAP1 expression in eosinophils converts Slit2 from a repulsive to an attractive cue, establishing cell-type-specific signaling output.

    Evidence Robo1-srGAP1 blocking experiments, Cdc42 activity pulldown, PI3K recruitment assays, leukocyte chemotaxis in neutrophils and eosinophils

    PMID:20944010

    Open questions at the time
    • Mechanism by which low srGAP1 levels permit PI3K recruitment to Robo1 is not biochemically defined
    • Not replicated in human primary leukocytes
  3. 2012 Medium

    Defining F-BAR domain-specific functions: unlike srGAP2/3 F-BAR domains that induce filopodia, the srGAP1 F-BAR domain suppresses filopodia and reduces plasma membrane dynamics, and heterodimerization among srGAP family F-BAR domains can synergistically modulate membrane remodeling.

    Evidence Overexpression in COS7 cells and cortical neurons, FRAP, filopodia quantification, heterodimerization assays

    PMID:22467852

    Open questions at the time
    • Endogenous stoichiometry and regulation of srGAP heterodimerization in neurons unknown
    • Membrane-binding mechanism of the srGAP1 F-BAR domain not structurally resolved
  4. 2013 High

    Resolving GTPase substrate specificity: in vitro GAP assays showed srGAP1 is Rac1-specific (not Cdc42 or RhoA), and its depletion overactivates Rac1 while inactivating RhoA, shifting cell motility from random to directionally persistent — establishing srGAP1 as a Rac1-RhoA balance regulator.

    Evidence In vitro GAP assay, siRNA knockdown, GST-PAK/rhotekin pulldowns, live-cell lamellipodia imaging

    PMID:24006490

    Open questions at the time
    • Apparent discrepancy with studies showing Cdc42-GAP activity in leukocytes and cancer cells is unresolved — cell-type or context dependence not systematically tested
    • No reconstitution with full-length protein and membranes
  5. 2013 Medium

    Linking SRGAP1 mutations to human disease: missense variants in the F-BAR (Q149H) and RhoGAP (R617C) domains from papillary thyroid carcinoma families impaired CDC42 inactivation, providing the first functional evidence connecting SRGAP1 loss-of-function to tumorigenesis.

    Evidence Biochemical GTPase inactivation assays with patient-derived mutant constructs

    PMID:23539728

    Open questions at the time
    • Causality not established in animal models
    • Only two variants tested; spectrum of functional mutation effects unknown
  6. 2015 Medium

    Extending the Slit2-Robo1-srGAP1-Cdc42 axis to kidney development: gain-of-function SRGAP1 mutations from CAKUT families augmented RAC1 inhibition in HEK cells, and SRGAP1 colocalizes with ROBO2 in SIX2-positive nephron progenitors, implicating this pathway in renal morphogenesis.

    Evidence Whole-exome sequencing, RAC1 GTPase pulldown with mutant SRGAP1 in HEK cells, immunofluorescence in developing kidney

    PMID:26026792

    Open questions at the time
    • No in vivo kidney-specific knockout to confirm functional role in nephrogenesis
    • Whether SRGAP1 signals through ROBO2 or ROBO1 in this context is untested
  7. 2015 Medium

    Establishing srGAP1 as a neuroinflammatory mediator: in rat surgical brain injury, srGAP1 mediated Slit2-dependent suppression of immune cell infiltration via Cdc42 inactivation, with siRNA reversal confirming pathway necessity.

    Evidence srGAP1 siRNA in rat SBI model, Cdc42 activity assay, immunohistochemistry

    PMID:26550694

    Open questions at the time
    • Specific immune cell types affected not delineated
    • No genetic loss-of-function model used
  8. 2017 High

    Revealing a Robo-independent role at cell-cell junctions: tyrosine-dephosphorylated cortactin recruits SRGAP1 to epithelial adherens junctions where it antagonizes RhoA to reduce contractility, a mechanism co-opted by HGF for junctional relaxation and collective motility.

    Evidence Cortactin phosphorylation mutants, RhoA activity assays, SRGAP1 RNAi, traction force microscopy, laser ablation tension measurements, live imaging of epithelial junctions

    PMID:28983097 PMID:29160905

    Open questions at the time
    • How cortactin-SRGAP1 interaction is structurally mediated (direct vs. indirect binding) not resolved
    • Whether RhoA is a direct GAP substrate at junctions or indirectly regulated via Rac1 cross-talk is unclear
  9. 2021 High

    Demonstrating in vivo requirement in podocytes: conditional podocyte-specific Srgap1 knockout mice develop FSGS-like foot-process effacement with disinhibited Rho GTPase signaling, and quantitative interaction proteomics linked SRGAP1 to protrusive and contractile actin networks.

    Evidence Conditional knockout mouse (hNPHS2Cre), super-resolution and electron microscopy, CRISPR/Cas9 KO podocytes, proximity ligation assay, quantitative interaction proteomics

    PMID:33514561

    Open questions at the time
    • Which specific Rho GTPase(s) are deregulated in vivo in podocytes not determined
    • Therapeutic targetability of this pathway for FSGS not explored
  10. 2023 Medium

    Confirming the neuroinflammatory role of srGAP1 in a second brain injury model: in rat germinal matrix hemorrhage, srGAP1 siRNA abolished Slit2-mediated suppression of Cdc42-dependent immune cell infiltration, replicating the SBI findings.

    Evidence srGAP1 siRNA in rat GMH model, Cdc42 activity assay, Western blot, immunofluorescence

    PMID:37899442

    Open questions at the time
    • Mechanism by which Slit2 activates srGAP1 in brain tissue not defined beyond Robo1 binding
    • No conditional knockout confirmation in neuroinflammatory models

Open questions

Synthesis pass · forward-looking unresolved questions
  • The apparent substrate discrepancy — Cdc42-specific GAP activity in immune/cancer contexts versus Rac1-specific activity in fibroblasts and RhoA antagonism at epithelial junctions — remains mechanistically unresolved; whether context-dependent post-translational modifications, binding partners, or membrane localization dictate substrate preference is unknown.
  • No systematic side-by-side comparison of GAP specificity across cell types with purified full-length protein
  • Full-length structure not available to explain how F-BAR and SH3 domains modulate GAP domain specificity
  • In vivo substrate identity in each physiological context has not been genetically validated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 6
Localization
GO:0005886 plasma membrane 3 GO:0005829 cytosol 2
Pathway
R-HSA-162582 Signal Transduction 6 R-HSA-168256 Immune System 3 R-HSA-1500931 Cell-Cell communication 2
Partners
CDC42CTTNRAC1RHOAROBO1SRGAP2SRGAP3

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2006 Crystal structure of the srGAP1 SH3 domain at 1.8-Å resolution revealed that it binds the proline-rich CC2 and CC3 motifs of the Robo intracellular domain; surface plasmon resonance showed binding occurs in a C-to-N orientation, with the N-terminal two acidic residues of CC3 required for interaction. X-ray crystallography (1.8 Å), surface plasmon resonance binding assays, peptide mutagenesis The Journal of Biological Chemistry High 16857672
2010 In neutrophils, Slit2 activates srGAP1 downstream of Robo1, leading to Cdc42 inactivation and suppression of chemotaxis; blockade of srGAP1 binding to Robo1 reversed this repulsive signaling. In eosinophils, lower srGAP1 expression allows Cdc42 activation and PI3K recruitment to Robo1, converting Slit2 signaling from repulsive to attractive. Robo1-srGAP1 blocking experiments, Cdc42 activity assays, PI3K recruitment assays, leukocyte chemotaxis assays in eosinophils and neutrophils Journal of Immunology Medium 20944010
2012 The F-BAR domain of srGAP1 (F-BAR(1)) prevents filopodia formation in cortical neurons and reduces plasma membrane dynamics, in contrast to srGAP2 and srGAP3 F-BAR domains; the three F-BAR domains can heterodimerize and act synergistically toward filopodia induction in COS7 cells. F-BAR(1) displays the slowest molecular dynamics at the plasma membrane as measured by FRAP. Overexpression in COS7 cells and cortical neurons, FRAP, filopodia quantification, heterodimerization assays Journal of Cell Science Medium 22467852
2013 srGAP1 has GAP activity specific to Rac1 (not Cdc42 or RhoA), is recruited to lamellipodia in a Rac1-dependent manner, limits Rac1 activity to allow concomitant RhoA activation, and thereby restricts lamellipodial protrusion and promotes membrane ruffling. Depletion of srGAP1 overactivates Rac1, inactivates RhoA, and shifts cell motility from random to directionally persistent. siRNA knockdown, GTPase activity assays (GST-PAK pulldown for Rac1, rhotekin for RhoA), live-cell imaging of lamellipodia, GAP activity in vitro assay Molecular Biology of the Cell High 24006490
2013 Two missense variants in the F-BAR domain (Q149H) and RhoGAP domain (R617C) of SRGAP1, identified in PTC families, severely impaired its ability to inactivate CDC42 in biochemical assays. Biochemical GTPase inactivation assays with mutant SRGAP1 constructs The Journal of Clinical Endocrinology and Metabolism Medium 23539728
2015 srGAP1 mediates Slit2/Robo1-dependent inhibition of peripheral immune cell infiltration after surgical brain injury by suppressing Cdc42 activity; srGAP1 siRNA knockdown reversed the protective effects of recombinant Slit2. siRNA knockdown in rat SBI model, Cdc42 activity assay, Western blot, immunohistochemistry Neurobiology of Disease Medium 26550694
2015 Two heterozygous SRGAP1 mutations identified in CAKUT families lead to augmented inhibition of RAC1 (gain-of-function for RAC1-GAP activity) in cultured human embryonic kidney cells; SRGAP1 is coexpressed with ROBO2 in SIX2-positive nephron progenitor cells. Whole-exome sequencing, RAC1 activity assay (GTPase pulldown) in HEK cells expressing mutant SRGAP1, immunofluorescence colocalization in developing kidney Human Genetics Medium 26026792
2016 srGAP1 physically interacts with Robo1 (co-immunoprecipitation), colocalizes with Robo1 after Slit2 treatment in colorectal cancer cells, and mediates Slit2-Robo1-dependent inhibition of Cdc42 activity and cell migration. Co-immunoprecipitation, immunofluorescence colocalization, Cdc42 GTPase pulldown assay, wound-healing migration assay Journal of Experimental & Clinical Cancer Research Medium 27923383
2017 Tyrosine-dephosphorylated cortactin recruits SRGAP1 to epithelial adherens junctions, where SRGAP1 acts as a RhoA antagonist to downregulate junctional contractility; this pathway is co-opted by HGF to promote junctional relaxation and collective motility. Cortactin phosphorylation mutants, RhoA activity assays, SRGAP1 RNAi, traction force microscopy, live imaging of epithelial junctions Nature Communications High 28983097
2017 SRGAP1 is present at subconfluent epithelial junctions and actively suppresses RhoA signaling and contractility; SRGAP1 RNAi in subconfluent Caco-2 cells restores RhoA signaling and junctional tension to levels seen in confluent monolayers, demonstrating regulated recruitment of SRGAP1 controls junctional maturation. SRGAP1 RNAi, RhoA activity assay, laser ablation for junctional tension measurement, immunofluorescence Cytoskeleton Medium 29160905
2017 SRGAP1 knockdown in gastric cancer cells inhibits Wnt/β-catenin pathway activity, as demonstrated by luciferase reporter assays, and suppresses cell proliferation, colony formation, invasion, and migration. siRNA knockdown, dual luciferase reporter assay for Wnt/β-catenin, colony formation, invasion/migration assays Oncogene Medium 29234151
2019 srGAP1 acts downstream of Robo1 to mediate neuroprotection by Slit2 in neonatal HIE; recombinant Slit2 reduced neuronal apoptosis via RhoA inhibition, and srGAP1-siRNA knockdown reversed these effects. srGAP1 siRNA in rat neonatal HIE model, Western blot for RhoA pathway, TUNEL/Fluoro-Jade C staining Neuropharmacology Medium 31356825
2021 SRGAP1 localizes to podocyte foot processes in vivo and cellular protrusions in vitro; conditional podocyte-specific Srgap1 knockout mice develop FSGS-like foot-process effacement, and SRGAP1-knockout podocytes show excessive protrusion formation and disinhibition of the Rho GTPase machinery. Quantitative interaction proteomics linked SRGAP1 to protrusive and contractile actin networks. Conditional knockout mouse (hNPHS2Cre), in situ proximity ligation assay for localization, super-resolution and electron microscopy, CRISPR/Cas9 KO podocytes, quantitative interaction proteomics Journal of the American Society of Nephrology High 33514561
2023 srGAP1 mediates Slit2/Robo1 suppression of Cdc42-dependent peripheral immune cell infiltration in a rat germinal matrix hemorrhage model; srGAP1 siRNA knockdown abolished the anti-neuroinflammatory effects of recombinant Slit2. srGAP1 siRNA in rat GMH model, Cdc42 activity assay, Western blot, immunofluorescence Journal of Neuroinflammation Medium 37899442

Source papers

Stage 0 corpus · 16 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility. The Journal of clinical endocrinology and metabolism 69 23539728
2012 The F-BAR domains from srGAP1, srGAP2 and srGAP3 regulate membrane deformation differently. Journal of cell science 64 22467852
2010 Slit2 regulates attractive eosinophil and repulsive neutrophil chemotaxis through differential srGAP1 expression during lung inflammation. Journal of immunology (Baltimore, Md. : 1950) 57 20944010
2015 Mutations of the SLIT2-ROBO2 pathway genes SLIT2 and SRGAP1 confer risk for congenital anomalies of the kidney and urinary tract. Human genetics 53 26026792
2010 The corticofugal neuron-associated genes ROBO1, SRGAP1, and CTIP2 exhibit an anterior to posterior gradient of expression in early fetal human neocortex development. Cerebral cortex (New York, N.Y. : 1991) 44 21060114
2015 Recombinant Slit2 attenuates neuroinflammation after surgical brain injury by inhibiting peripheral immune cell infiltration via Robo1-srGAP1 pathway in a rat model. Neurobiology of disease 37 26550694
2017 SRGAP1, a crucial target of miR-340 and miR-124, functions as a potential oncogene in gastric tumorigenesis. Oncogene 33 29234151
2013 srGAP1 regulates lamellipodial dynamics and cell migratory behavior by modulating Rac1 activity. Molecular biology of the cell 33 24006490
2016 srGAP1 mediates the migration inhibition effect of Slit2-Robo1 in colorectal cancer. Journal of experimental & clinical cancer research : CR 30 27923383
2017 Tyrosine dephosphorylated cortactin downregulates contractility at the epithelial zonula adherens through SRGAP1. Nature communications 28 28983097
2006 Structural basis of Robo proline-rich motif recognition by the srGAP1 Src homology 3 domain in the Slit-Robo signaling pathway. The Journal of biological chemistry 25 16857672
2021 SRGAP1 Controls Small Rho GTPases To Regulate Podocyte Foot Process Maintenance. Journal of the American Society of Nephrology : JASN 23 33514561
2019 Recombinant Slit2 attenuates neuronal apoptosis via the Robo1-srGAP1 pathway in a rat model of neonatal HIE. Neuropharmacology 15 31356825
2023 Recombinant Slit2 suppresses neuroinflammation and Cdc42-mediated brain infiltration of peripheral immune cells via Robo1-srGAP1 pathway in a rat model of germinal matrix hemorrhage. Journal of neuroinflammation 11 37899442
2017 Regulated recruitment of SRGAP1 modulates RhoA signaling for contractility during epithelial junction maturation. Cytoskeleton (Hoboken, N.J.) 10 29160905
2023 In silico whole-transcriptome analysis reveals a potential hsa_circ_0000375-miR-424-5p-TPM2/SRPX/SRGAP1 regulatory network related to liver metastasis of colorectal cancer. Heliyon 4 37954397