{"gene":"GRB10","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1995,"finding":"GRB10 was cloned as a new SH2 domain protein by screening expression libraries with the tyrosine-phosphorylated EGF receptor C-terminus. It contains an SH2 domain and a central domain with similarity to a C. elegans gene. At least three forms exist in fibroblasts from alternate translational start sites. GRB10 undergoes serine but not tyrosine phosphorylation after EGF treatment. GRB10 binds poorly to the EGF receptor, suggesting a different binding partner.","method":"Expression library screening, co-immunoprecipitation, phosphorylation assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — original cloning paper with multiple methods (library screen, IP, phosphorylation assays), single lab","pmids":["7731717"],"is_preprint":false},{"year":1995,"finding":"GRB10 SH2 domain interacts with the RET receptor tyrosine kinase in a phosphorylation/activation-dependent manner, as demonstrated by yeast two-hybrid screen and GST pulldown. GRB10 is the first identified signaling intermediate for RET.","method":"Yeast two-hybrid screen, GST fusion protein pulldown, in vivo co-immunoprecipitation using EGFR/Ret chimera","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus in vitro pulldown plus in vivo co-IP, single lab","pmids":["7665556"],"is_preprint":false},{"year":1996,"finding":"GRB10 SH2 domain binds the insulin receptor (IR) in an insulin-dependent, kinase-activity-dependent manner. The interaction requires the IR C-terminus, with highest affinity for phosphopeptide containing pTyr-1322. GRB10 does not associate with IRS-1, suggesting an IRS-1-independent function of the IR C-terminus.","method":"Yeast two-hybrid, GST fusion protein pulldown with purified IR, co-precipitation from cell extracts, phosphopeptide binding assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified components plus mutagenesis plus cell-based co-IP, replicated across multiple approaches in single study","pmids":["8621530"],"is_preprint":false},{"year":1996,"finding":"GRB10 SH2 domain interacts with the IGF-I receptor (IGF-IR) in a tyrosine kinase-active, receptor-dependent manner, not requiring juxtamembrane Tyr950. GRB10 co-precipitates with IGF-IR in cell lysates. Microinjection of GRB10 SH2 domain fusion protein inhibited insulin- and IGF-I-stimulated mitogenesis but not EGF-stimulated mitogenesis in fibroblasts.","method":"Yeast two-hybrid (interaction trap), Western blotting of yeast extracts, microinjection of GST-SH2 fusion protein, DNA synthesis assay","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus functional microinjection assay, single lab","pmids":["8776723"],"is_preprint":false},{"year":1996,"finding":"Ligand-activated ELK receptor tyrosine kinase (Eph family) associates with GRB10 via SH2 domain interaction at ELK phospho-Tyr-929 in vascular endothelial cells. This association is phosphorylation-dependent and occurs in vivo upon LERK-2/Fc stimulation.","method":"Yeast two-hybrid screen, site-directed mutagenesis, GST pulldown with phosphorylated recombinant ELK, co-immunoprecipitation from endothelial cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid, mutagenesis, in vitro pulldown and in vivo co-IP, single lab","pmids":["8798570"],"is_preprint":false},{"year":1996,"finding":"GRB10/IR-SV1 SH2 domain interacts specifically in vitro with insulin receptor derived from mammalian cells and with IGF-I receptor. Microinjection of the SH2 domain fusion protein inhibited insulin- and IGF-I-stimulated mitogenesis but not EGF-stimulated mitogenesis in fibroblasts.","method":"Yeast two-hybrid, GST fusion protein in vitro binding, microinjection into fibroblasts, DNA synthesis assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro binding plus functional microinjection, single lab","pmids":["8798417"],"is_preprint":false},{"year":1997,"finding":"GRB10 protein translocates from cytosol to membrane upon insulin stimulation, mediated by direct interactions with the insulin receptor via SH2 domain and additional regions. The SH2 domain binds at least two sites in the IR: the kinase activation loop and the juxtamembrane site. GRB10 also binds c-Abl SH3 domain via a conserved site, as well as PDGF and EGF receptors.","method":"Cell fractionation, co-immunoprecipitation, synthetic phosphopeptide binding assays, mutated receptor studies","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell fractionation plus phosphopeptide binding plus co-IP, single lab","pmids":["9006901"],"is_preprint":false},{"year":1997,"finding":"GRB10 interacts preferentially with insulin receptor over IGF-I receptor in intact mouse fibroblasts. Hormone-activated IR co-precipitated with three GRB10 isoforms, whereas GRB10 was essentially undetectable in IGF-IR immunoprecipitates under the same conditions.","method":"Co-immunoprecipitation from R-IR and R+ cell lines with hormone stimulation","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean receptor-specific co-IP in defined cell lines, single lab","pmids":["9062339"],"is_preprint":false},{"year":1998,"finding":"GRB10 contains a second novel kinase-activity-dependent binding domain, the BPS domain (between PH and SH2), located in ~50 amino acids. The BPS domain interacts with IR and IGF-IR in a kinase-dependent manner requiring the activation loop phosphotyrosines (Y1150/Y1151). The IR interacts with both BPS and SH2 domains; IGF-IR preferentially with BPS; EGFR preferentially with SH2.","method":"Domain mapping, site-directed mutagenesis of IR activation loop (Y1150F/Y1151F), GST pulldown, yeast two-hybrid","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis plus in vitro pulldown with domain mapping, multiple orthogonal methods in single study","pmids":["9506989"],"is_preprint":false},{"year":1998,"finding":"GRB10 SH2 domain interacts with Raf-1 and MEK1 kinases in a phosphotyrosine-independent manner. Interaction with Raf-1 is constitutive; interaction with MEK1 requires insulin treatment and follows MAPK activation. Mutation of MEK1 Thr-386 reduces binding. SH2 domain residues Arg-βB5 and Asp-EF2 are required for binding both receptors and kinases. Overexpression of SH2 domain mutants induces apoptosis reversible by wild-type co-expression.","method":"Yeast two-hybrid, random mutagenesis of SH2 domain, site-directed mutagenesis of MEK1, transfection/apoptosis assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid with mutagenesis plus cell-based functional assays, single lab","pmids":["9553107"],"is_preprint":false},{"year":1998,"finding":"GRB10 interacts with GHR (growth hormone receptor) and JAK2 upon GH stimulation in Huh-7 hepatoma cells. GRB10 inhibits transcription of SRE of c-fos and GH response element 2 of Spi2.1 reporter genes but has no effect on STAT5-dependent reporter genes, placing GRB10 as a downstream inhibitor of GH signaling via JAK2 but independent of STAT5.","method":"Phage library screening with phosphorylated GHR cytoplasmic domain, co-immunoprecipitation from Huh-7 cells, co-transfection reporter assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus functional reporter assays, single lab","pmids":["9632636"],"is_preprint":false},{"year":1998,"finding":"GRB10/GrbIR is an in vivo substrate of Tec tyrosine kinase. In HEK293 cells, GRB10 becomes profoundly tyrosine-phosphorylated by Tec but not by Syk, JAK2, or insulin receptor. GRB10 expression suppresses Tec-driven and cytokine-driven activation of the c-fos promoter.","method":"Yeast two-hybrid screen, transient expression tyrosine phosphorylation assay in HEK293 cells, reporter gene assay","journal":"Genes to cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo phosphorylation assay with kinase specificity controls plus functional reporter, single lab","pmids":["9753425"],"is_preprint":false},{"year":1998,"finding":"GRB10 interacts with BCR-ABL in a phosphotyrosine-dependent manner at Bcr sites (aa242-446), distinct from the Grb2 binding site. This interaction is kinase-activation-dependent in vivo. A BCR-ABL mutant lacking GRB10 interaction (Bcr/1-242-Abl) partially reduced IL-3 independence and focus formation, indicating GRB10 interaction is important for BCR-ABL transforming function.","method":"Yeast two-hybrid with LexA-BCR-ABL bait, in vitro binding, co-immunoprecipitation from CML cells, functional IL-3 independence and focus formation assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid, in vitro binding, in vivo co-IP and functional transformation assays, single lab","pmids":["9747873"],"is_preprint":false},{"year":1999,"finding":"Endogenous GRB10 localizes predominantly to mitochondria (peripherally associated), as shown by immunofluorescence and subcellular fractionation. Small pools translocate to plasma membrane and actin-rich ruffles after IGF-I or serum treatment. GRB10 co-immunoprecipitates with Raf-1 from mitochondrial fractions, and this interaction is enhanced by UV-induced Raf-1 activation. The GRB10-binding site on Raf-1 co-localizes with the Ras-binding domain.","method":"Immunofluorescence microscopy, subcellular fractionation, co-immunoprecipitation from mitochondrial fraction, yeast two-hybrid","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immunofluorescence plus fractionation plus co-IP with functional context, single lab","pmids":["10585452"],"is_preprint":false},{"year":1999,"finding":"GRB10 acts as a positive stimulatory signaling adapter in PDGF-BB-, IGF-I-, and insulin-mediated mitogenesis in normal fibroblasts. PDGF receptor β Y771 is required for GRB10 SH2 domain association. Multiple independent strategies (cDNA overexpression, SH2 domain microinjection, cell-permeable peptides) consistently support a positive mitogenic role distinct from EGF.","method":"Ecdysone-regulated overexpression, microinjection, cell-permeable Drosophila antennapedia homeodomain fusion peptides, cell proliferation/DNA synthesis assays, co-immunoprecipitation","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — four independent experimental strategies in same lab, though contradicted by other studies","pmids":["10454568"],"is_preprint":false},{"year":2000,"finding":"GRB10 is phosphorylated on tyrosine (Tyr67) by Src and Fyn kinases but not by the insulin receptor kinase directly. Src/Fyn-mediated phosphorylation negatively regulates GRB10 binding to the IR; a Y67G GRB10 mutant shows higher affinity for IR.","method":"In vitro kinase assays with purified Src/Fyn, herbimycin A inhibitor, dominant-negative/constitutively-active Src/Fyn transfection, site-directed mutagenesis (Y67G), co-immunoprecipitation","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay plus mutagenesis plus cell-based functional binding assays with multiple orthogonal methods","pmids":["10871840"],"is_preprint":false},{"year":2001,"finding":"GRB10 BPS domain directly inhibits substrate phosphorylation by activated tyrosine kinase domains of IR and IGF-1R in vitro. Inhibition is dependent on activation-loop phosphorylation but peptide competition shows the BPS domain does not bind phosphotyrosine directly, providing a pseudosubstrate-like inhibition mechanism.","method":"In vitro kinase assay with purified recombinant BPS domain and tyrosine kinase domains, phosphopeptide competition experiments","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro with purified recombinant proteins plus competition experiments; establishes direct biochemical mechanism","pmids":["11287005"],"is_preprint":false},{"year":2001,"finding":"GRB10 associates with VEGF receptor KDR (VEGFR-2) in response to VEGF stimulation and positively regulates KDR levels and tyrosine phosphorylation. GRB10 tyrosine phosphorylation in response to VEGF requires an intact SH2 domain and is partially mediated by Src. The positive effect on KDR is independent of GRB10 SH2 domain.","method":"Co-immunoprecipitation from HUVEC and 293/KDR cells, GRB10 mutant overexpression, qRT-PCR, MAPK signaling readout","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus domain mutagenesis plus signaling readouts, single lab","pmids":["11494124"],"is_preprint":false},{"year":2002,"finding":"GRB10 inhibits IRS-1/IRS-2 PI3K/Akt signaling by physically blocking IRS access to the IR via its SH2 domain. Overexpression reduced insulin-stimulated IRS-1/2 tyrosine phosphorylation and delayed/reduced Akt phosphorylation. Yeast tri-hybrid assays showed GRB10 blocks IR-IRS association. GRB10 does not affect IR catalytic activity toward Tyr972 or Tyr1158/1162/1163.","method":"Overexpression in CHO/IR cells and adipocytes, yeast tri-hybrid assay, phosphorylation time-course, co-immunoprecipitation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast tri-hybrid plus cell-based phosphorylation assays with mutagenesis context, single lab","pmids":["12493740"],"is_preprint":false},{"year":2002,"finding":"GRB10 forms a constitutive complex with Akt, and GRB10 co-expression with c-kit synergistically activates Akt in a wortmannin-sensitive, PI3K-independent manner downstream of PI3K. GRB10 is recruited to c-kit via SH2 domain in a phosphotyrosine-dependent manner. Both SH2 and PH domains of GRB10 are required for Akt activation.","method":"Yeast two-hybrid screen with c-kit cytoplasmic domain, co-immunoprecipitation, Akt kinase assay, dominant-negative/deletion mutants, wortmannin inhibition, Ba/F3 IL-3 independence assay","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus kinase assay plus functional IL-3 independence, multiple methods single lab","pmids":["11809791"],"is_preprint":false},{"year":2003,"finding":"GRB10 forms a complex with Nedd4 E3 ubiquitin ligase and IGF-IR. GRB10 promotes ligand-dependent ubiquitination and accelerated internalization and degradation of IGF-IR via both proteasomal and lysosomal pathways. Catalytically inactive Nedd4-CS mutant or GRB10 mutant lacking SH2 domain both impair IGF-IR ubiquitination. GRB10 acts as an adapter bridging Nedd4 to IGF-IR.","method":"Co-immunoprecipitation, overexpression in mouse embryo fibroblasts, ubiquitination assay, receptor half-life measurement, inhibitors MG132 and chloroquine, dansylcadaverine treatment, Nedd4-CS catalytic mutant","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, ubiquitination assay with catalytic mutant controls, multiple inhibitor approaches, replicated with domain mutant; first demonstration of HECT E3 regulation of RTK stability","pmids":["12697834"],"is_preprint":false},{"year":2003,"finding":"GRB10 N-terminus interacts with two novel proteins, GIGYF1 and GIGYF2, via GYF domain binding to tandem proline-rich regions. In IGF-I-stimulated cells, GIGYF1 binding to GRB10 increases, and both transiently associate with IGF-IR, with GIGYF1 later dissociating while GRB10 remains. Overexpression of GRB10-binding GIGYF1 fragment increases IGF-I-stimulated receptor tyrosine phosphorylation.","method":"Yeast two-hybrid screen with GRB10 N-terminus bait, mutation analysis, co-immunoprecipitation from R+ fibroblasts, overexpression assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus cell-based co-IP plus functional overexpression, single lab","pmids":["12771153"],"is_preprint":false},{"year":2003,"finding":"GRB10 negatively regulates insulin-stimulated MAPK signaling by inhibiting Shc tyrosine phosphorylation in an SH2 domain-dependent manner. Overexpression reduced insulin-stimulated MAPK/Elk1 phosphorylation; RNAi knockdown enhanced MAPK, Shc, and Akt phosphorylation.","method":"Overexpression in CHO/IR cells and adipocytes, RNA interference in HeLa/IR cells, phosphorylation assays, SH2-deletion mutant","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain- and loss-of-function with domain mutant, single lab","pmids":["14615605"],"is_preprint":false},{"year":2003,"finding":"GRB10 functions as a critical component of the IR signaling complex linking IR to p85 PI3K, regulating PI3K activity and metabolic insulin responses (glycogen synthesis, glucose and amino acid transport, lipogenesis). Direct association between GRB10 and p85 was demonstrated; no association between GRB10 and IRS proteins was detected. Dominant-negative GRB10 SH2 domain and Pro-rich region abolished metabolic insulin response in 3T3-L1 adipocytes.","method":"Co-immunoprecipitation, PI3K activity assay, dominant-negative domain expression, metabolic assays in 3T3-L1 adipocytes and L6 cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, kinase activity assay, functional metabolic readouts, single lab","pmids":["12783867"],"is_preprint":false},{"year":2003,"finding":"The GRB10 SH2 domain forms a non-covalent dimer in solution under physiologic conditions. Crystal structure at 1.65 Å resolution reveals a dimer interface involving residues in/flanking the C-terminal alpha helix conserved in Grb7/10/14. Val-522 (BG loop) and Asp-500 (EF loop) position interferes with P+3 phosphopeptide binding, favoring dimeric turn-containing phosphotyrosine sequences such as IR/IGF-1R activation loops.","method":"X-ray crystallography (1.65 Å), analytical ultracentrifugation for dimerization in solution","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus solution biophysics, clear structural basis for ligand specificity","pmids":["12551896"],"is_preprint":false},{"year":2004,"finding":"GRB10 prevents Nedd4-mediated degradation of VEGF-R2. GRB10 constitutively associates with Nedd4. Co-expression of GRB10 and Nedd4 restores VEGF-R2 expression that is otherwise reduced by Nedd4. Nedd4 itself does not directly ubiquitinate VEGF-R2 (Nedd4C854S ligase-dead mutant retains VEGF-R2 ubiquitination). Thus GRB10 acts as a positive regulator protecting VEGF-R2 from Nedd4-mediated degradation.","method":"Co-immunoprecipitation, overexpression of Nedd4 and GRB10 in cells, Nedd4-CS catalytic mutant, MG132 proteasome inhibitor, ubiquitination assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus functional assays with catalytic mutant control, single lab","pmids":["15060076"],"is_preprint":false},{"year":2005,"finding":"Endogenous GRB10 knockdown by siRNA enhances IGF-I-mediated phosphorylation of IRS proteins, Akt, and ERK1/2 and increases DNA synthesis. Knockdown also decreases IGF-I-stimulated receptor autophosphorylation, partially reversed by pervanadate (phosphatase inhibitor), indicating GRB10 blocks phosphatase access to the activated IGF-IR. GIGYF proteins interact specifically with GRB10 but not Grb7 or Grb14.","method":"siRNA knockdown, phosphorylation assays, DNA synthesis assay, pervanadate treatment, yeast two-hybrid specificity assays","journal":"Endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA loss-of-function with multiple signaling readouts and pharmacological evidence for mechanism, single lab","pmids":["16037382"],"is_preprint":false},{"year":2005,"finding":"GRB10 N-terminal domains (absent in BPS-SH2 fragment) are required for effects on IR autophosphorylation and glucose uptake in 3T3-L1 adipocytes. Full-length GRB10 inhibits IR autophosphorylation and glucose uptake, while BPS-SH2 fragment inhibits post-receptor signaling (IRS1, IRS2, Akt, Shc, ERK, APS, c-Cbl) but not receptor phosphorylation or glucose uptake despite more sustained IR binding.","method":"Overexpression of full-length vs. truncated GRB10, glucose uptake assay, phosphorylation assays, co-precipitation","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain deletion analysis with multiple functional and biochemical readouts, single lab","pmids":["15664450"],"is_preprint":false},{"year":2006,"finding":"GRB10 mediates insulin-stimulated ubiquitination and proteasomal degradation of the insulin receptor. Suppression of endogenous GRB10 increased IR protein levels without affecting IR mRNA, and blocked insulin-induced IR ubiquitination and reduction. Overexpression of GRB10 reduced IR protein levels. MG132 (proteasomal inhibitor) but not chloroquine (lysosomal inhibitor) reversed IR reduction.","method":"Stable overexpression and RNAi knockdown cell lines, mRNA/protein level analysis, ubiquitination assay, MG132 and chloroquine treatment","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — bidirectional gain/loss of function with mechanistic dissection using inhibitors, single lab","pmids":["16434550"],"is_preprint":false},{"year":2007,"finding":"Peripheral disruption of Grb10 (maternal allele) in mice leads to overgrowth and enhanced insulin-stimulated Akt and MAPK phosphorylation in skeletal muscle and fat. Hyperinsulinemic-euglycemic clamp studies revealed increased insulin sensitivity in peripheral tissues, establishing GRB10 as a negative regulator of insulin signaling and action in vivo.","method":"Gene trap knockout mice (maternal allele), hyperinsulinemic-euglycemic clamp, phosphorylation assays in tissues","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic KO with gold-standard clamp studies and tissue signaling, replicated across multiple insulin target tissues","pmids":["17620412"],"is_preprint":false},{"year":2007,"finding":"Adult Grb10Δ2-4 knockout mice show improved glucose tolerance, insulin sensitivity, increased muscle mass, and reduced adiposity. Tissue-specific IR tyrosine phosphorylation changes are consistent with GRB10 preventing phosphatases from accessing IR activation-loop phosphotyrosines. Insulin-induced IRS-1 phosphorylation is enhanced, supporting GRB10 attenuation of IR-to-IRS-1 signal transmission.","method":"Grb10 gene disruption mouse model, glucose tolerance and insulin tolerance tests, IR/IRS-1 phosphorylation assays, body composition analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO model with multiple metabolic and biochemical endpoints; mechanistic model supported by phosphorylation pattern","pmids":["17562854"],"is_preprint":false},{"year":2005,"finding":"Phosphorylation of GRB10 serine 428 by Akt creates a binding site for 14-3-3 proteins. Mutation of Ser428 diminishes 14-3-3 binding. Akt directly binds GRB10 constitutively and phosphorylates GRB10 on Ser428 in an in vitro kinase assay.","method":"Yeast two-hybrid screen for 14-3-3 interaction, site-directed mutagenesis (S428), co-immunoprecipitation, in vitro Akt kinase assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay plus mutagenesis plus co-IP, single lab","pmids":["15722337"],"is_preprint":false},{"year":2007,"finding":"GRB10 and active Raf-1 promote Bad-dependent cell survival. Both GRB10-deficient and Raf-1-deficient MEFs show enhanced apoptosis upon Bad expression. GRB10 SH2, PH, and proline-rich domains plus Akt phosphorylation site and 14-3-3 binding are required for anti-apoptotic function. Raf-1 kinase activity, Src phosphorylation (Tyr340/341), and Ras-binding domain interaction with GRB10 SH2 are required. GRB10 and Raf-1 are required for PI3K/Akt and MAPK pathways to phosphorylate and inactivate Bad.","method":"KO MEFs from Grb10 and Raf-1 knockout mice, Bad overexpression apoptosis assay, structure-function analysis with domain mutants, siRNA, signaling inhibitor studies, mutagenesis of Bad phosphorylation sites","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO cells plus domain mutagenesis plus siRNA, multiple orthogonal approaches, single lab","pmids":["17535812"],"is_preprint":false},{"year":2008,"finding":"The GRB10/Nedd4 complex mediates multiubiquitination (not polyubiquitination) of IGF-IR upon ligand stimulation, which is required for receptor internalization via both clathrin-dependent and -independent pathways. GRB10 and Nedd4 remain associated with IGF-IR in early endosomes and caveosomes and are not degraded themselves, potentially being directed to recycling endosomes.","method":"Ubiquitination assays with K48R/K63R ubiquitin mutants, internalization assays, subcellular fractionation, co-immunoprecipitation from endosomes","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitin mutant assays plus fractionation plus co-IP, single lab","pmids":["18286479"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of GRB10 RA and PH domains at 2.6 Å reveals these domains and the intervening linker form an integrated, dimeric structural unit. Biochemical studies showed Grb14 binds activated Ras, suggesting Ras binding may serve as a timing mechanism for downregulation of insulin signaling. Results illuminate membrane-recruitment mechanisms of GRB7/10/14 family and related actin-cytoskeleton proteins.","method":"X-ray crystallography (2.6 Å resolution), biochemical Ras binding assays","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus biochemical validation, rigorous structural study","pmids":["19648926"],"is_preprint":false},{"year":2009,"finding":"GRB10 knockdown in human pancreatic islets reduces insulin and glucagon secretion, suggesting GRB10 plays a role in islet function beyond its known role in insulin signaling.","method":"siRNA knockdown in human pancreatic islets, insulin and glucagon secretion assays","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown in primary human islets with functional secretion readout, single study","pmids":["24699409"],"is_preprint":false},{"year":2010,"finding":"Crystal structure of NEDD4 C2 domain – GRB10 SH2 complex at 2.0 Å reveals three interaction interfaces. Main interface is an antiparallel β-sheet between GRB10 SH2 F-strand and NEDD4 C2 C-strand. NEDD4 C2 binds at non-classical sites far from the phosphotyrosine-binding pocket, making the interaction phosphotyrosine-independent. GRB10 SH2 can simultaneously bind NEDD4 C2 and IGF1R kinase domain.","method":"X-ray crystallography (2.0 Å), structural analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure providing atomic-level mechanism for GRB10 as adapter bridging NEDD4 to IGF1R","pmids":["20980250"],"is_preprint":false},{"year":2011,"finding":"GRB10 is a direct substrate of mTORC1. mTORC1-mediated phosphorylation stabilizes GRB10 protein. Phosphorylated GRB10 acts as a feedback inhibitor of the PI3K and ERK-MAPK pathways. Identified by large-scale quantitative phosphoproteomics.","method":"Quantitative phosphoproteomics (large-scale), mTORC1 kinase assay, rapamycin treatment, GRB10 stability assays, pathway readouts","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 / Strong — phosphoproteomics discovery plus kinase substrate validation plus functional pathway inhibition, replicated across multiple cell systems","pmids":["21659605"],"is_preprint":false},{"year":2011,"finding":"Within the brain, Grb10 is expressed from the paternal allele (not maternal as in peripheral tissues), and ablation of paternal Grb10 increases social dominance and allogrooming behavior. Loss of the peripherally-expressed maternal allele causes fetal and placental overgrowth. Thus the two parental alleles function in different tissues to influence distinct physiological processes.","method":"Conditional knockout mice (paternal vs maternal allele ablation), behavioral testing, body weight/placental weight measurement","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — allele-specific conditional KO with well-characterized behavioral and physiological phenotypes, published in high-impact journal with rigorous controls","pmids":["21270893"],"is_preprint":false},{"year":2012,"finding":"GRB10 deletion in mice increases myofiber number (not myofiber size) by 142% in skeletal muscle, with increased muscle mass maintained through 12 months. The hypermuscularity arises during embryonic development. Neonatal Grb10-deficient hindlimbs show increased functional gene signatures for myogenic signaling and proliferation.","method":"Grb10 knockout mice, histomorphometry (fiber number/size), gene expression profiling, neonatal tissue analysis","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with quantitative histomorphometry and gene expression, single lab","pmids":["22623587"],"is_preprint":false},{"year":2012,"finding":"GRB10 physically associates with FLT3 via FLT3 phospho-Tyr572 and Tyr793 in response to FLT3-ligand stimulation, and constitutively with oncogenic FLT3-ITD. GRB10 enhances FL-induced Akt phosphorylation by direct interaction with p85 PI3K subunit downstream of FLT3. GRB10 expression increases STAT5 activation in FLT3-ITD cells and promotes S-phase progression and survival.","method":"Co-immunoprecipitation (endogenous and overexpressed), phospho-mutant FLT3 constructs, Akt/ERK/p38 phosphorylation assays, siRNA knockdown, p85 interaction studies, cell cycle analysis","journal":"Molecular oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with phospho-mutants plus downstream signaling, single lab","pmids":["23246379"],"is_preprint":false},{"year":2014,"finding":"mTOR-mediated phosphorylation of GRB10 at Ser501/503 switches its binding preference from the insulin receptor to raptor (mTORC1 component), leading to dissociation of raptor from mTOR and downregulation of mTORC1 signaling as a feedback mechanism. Fat-specific disruption of GRB10 increased mTORC1 signaling in adipose tissue, suppressed lipolysis, and reduced thermogenic function, effects reversed by rapamycin.","method":"mTOR phosphorylation assays, phospho-specific mutagenesis (S501/503), raptor co-immunoprecipitation, fat-specific Grb10 KO mice, lipolysis assay, thermogenesis measurement, rapamycin rescue","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 1 / Strong — phospho-mutagenesis plus co-IP plus in vivo KO with rapamycin rescue, multiple orthogonal methods establishing feedback mechanism","pmids":["24746805"],"is_preprint":false},{"year":2007,"finding":"GRB10 binds to the intracellular portion of LRP6, the Wnt co-receptor, and negatively regulates Wnt signaling. GRB10 overexpression suppressed Wnt3a- and LRP6-induced TCF-dependent reporter activity upstream of β-catenin. RNAi knockdown of GRB10 enhanced Wnt3a-induced reporter activity. GRB10 interferes with Axin binding to LRP6 as the proposed mechanism.","method":"Co-immunoprecipitation, TCF reporter assays, RNAi knockdown, β-catenin accumulation assay, Axin binding competition","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus gain/loss-of-function reporter assays plus mechanistic Axin competition, single lab","pmids":["17376403"],"is_preprint":false},{"year":2008,"finding":"In mouse embryonic fibroblasts, GRB10 and Raf-1 form a complex that co-immunoprecipitates from mitochondrial fractions. GRB10 interacts with MEK1 in an insulin-dependent manner following MAPK activation. Direct GRB10-Gab1 association occurs in a peptide hormone-dependent manner via GRB10 SH2 domain binding to the Crk-binding region of Gab1, and elevated GRB10 potentiates MAPK-dependent mitogenesis in a Gab1-dependent manner.","method":"Peptide hormone-dependent co-immunoprecipitation, GRB10 SH2 domain peptide mimetic competition, Gab1 gene disruption cell lines, MAPK inhibitor studies, cell proliferation assays","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus KO cells plus inhibitor studies, single lab","pmids":["18985678"],"is_preprint":false},{"year":2009,"finding":"GRB10 adapter protein decreases total Kv1.3 potassium channel expression, particularly at the membrane surface, and eliminates BDNF-induced phosphorylation of Kv1.3 via interaction with basally phosphorylated Tyr111-113 and Tyr449 residues on the channel. Negative regulation by GRB10 prevents BDNF-induced current suppression of Kv1.3. GRB10 does not directly complex with Kv1.3 in HEK293 cells but co-immunoprecipitates with Kv1.3 in native olfactory bulb.","method":"Immunocytochemistry, co-immunoprecipitation from HEK293 and native olfactory bulb, Kv1.3 point mutations (tyrosine to phenylalanine), patch-clamp electrophysiology, Western blot for expression levels","journal":"BMC neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis plus electrophysiology plus co-IP, single lab","pmids":["19166614"],"is_preprint":false},{"year":2016,"finding":"GRB10 is activated downstream of TORC1 upon IL-4 stimulation in macrophages, associates with IRS-2, NEDD4.2, IL-4Rα and γC, and its knockdown enhances tyrosine phosphorylation of IRS-2 and M2 gene expression. IL-4Rα and γC are ubiquitinated after IL-4 stimulation, suggesting GRB10 regulates IL-4 receptor-signaling complex degradation through interactions with NEDD4.2.","method":"siRNA knockdown, co-immunoprecipitation, phosphorylation assays, M2 gene expression assays, ubiquitination assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA KD plus co-IP plus ubiquitination readout, single lab","pmids":["27742835"],"is_preprint":false},{"year":2016,"finding":"GRB10 deletion (maternal allele) substantially increases HSC long-term repopulating capacity and accelerates HSC regeneration after total body irradiation. GRB10-deficient HSCs show increased proliferation with upregulation of CDK4 and Cyclin E. Enhanced HSC regeneration is dependent on activation of the Akt/mTORC1 pathway.","method":"Grb10 maternal allele KO mice, competitive transplantation assay, total body irradiation reconstitution, CDK4/Cyclin E expression analysis, rapamycin treatment to test mTORC1 dependence","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo transplantation plus rapamycin rescue establishing pathway dependence, single lab","pmids":["27806297"],"is_preprint":false},{"year":2018,"finding":"Ablation of GRB10 specifically in muscle (using α-skeletal actin-Cre) is sufficient to cause muscle enlargement (increased fiber cross-sectional area) and increased insulin-stimulated glucose uptake with enhanced phospho-Akt in muscle. This confirms a muscle-autonomous role for GRB10 in growth and proximal insulin receptor signaling.","method":"Muscle-specific Cre-lox conditional KO (Grb10-mKO), hyperinsulinemic-euglycemic clamp, phospho-Akt assay in muscle","journal":"Endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific conditional KO with clamp studies establishing cell-autonomous role, single lab","pmids":["29370381"],"is_preprint":false},{"year":2018,"finding":"The Grb10 gene is silenced in adult mouse liver but can be reactivated by acute ER stress (tunicamycin or short-term high-fat diet) via ATF4-mediated transcriptional upregulation. Reactivated GRB10 promotes hepatic lipid dysregulation and steatosis; liver-specific GRB10 KO suppresses lipogenic gene expression and acute ER stress-induced hepatosteatosis.","method":"Liver-specific KO mice, tunicamycin/HFD challenge, ATF4 identification by luciferase reporter and ChIP/promoter analysis, hepatic lipid/gene expression assays","journal":"Journal of molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — liver-specific KO plus transcriptional mechanism identification, single lab","pmids":["29555819"],"is_preprint":false},{"year":2019,"finding":"GRB10 knockdown in human primary skeletal muscle myotubes enhances insulin-induced PI3K/Akt signaling and glucose uptake associated with increased insulin receptor abundance. mTORC1-mediated phosphorylation of GRB10 at Ser476 is stimulated by both insulin and amino acids independently and additively; rapamycin blocks this phosphorylation and disrupts negative feedback on PI3K/Akt, suggesting mTORC1 controls insulin receptor abundance via GRB10.","method":"siRNA knockdown in human primary myotubes, Ser476 phosphorylation assay, rapamycin treatment, glucose uptake assay, insulin receptor abundance measurement","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA KD in primary human cells plus phosphorylation assays with mTORC1 inhibitor, single lab","pmids":["31794259"],"is_preprint":false},{"year":2022,"finding":"An intronic secondary differentially methylated region (CBR2.3) within Grb10 on the paternal chromosome has tissue-specific paternal CTCF binding that functions as an insulator controlling allele-specific chromatin looping contacts with the neighboring Ddc gene. Deletion of paternal CBR2.3 removes this insulator, shifts chromatin looping, creates ectopic enhancer-promoter contacts, and destabilizes normal Grb10-Ddc allele-specific expression with developmental consequences in heart and muscle.","method":"Polymorphic mice, 4C-seq chromatin looping, allele-specific CTCF ChIP, conditional paternal CBR2.3 deletion, expression analysis, cardiac/muscle phenotyping","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — genetic deletion plus 3D chromatin mapping plus allele-specific expression in vivo, multiple orthogonal approaches","pmids":["36108632"],"is_preprint":false},{"year":2023,"finding":"GRB10 in hypothalamic AgRP and POMC neurons enhances leptin signaling and promotes weight loss. GRB10 interacts with the leptin receptor (LepR) in hypothalamic neurons. Ablation of GRB10 in AgRP neurons promotes weight gain; overexpression reduces body weight. GRB10 exaggerates inhibitory effects of leptin on AgRP neurons via ATP-sensitive potassium channel (KATP) currents and facilitates leptin's excitatory drive on POMC neurons via TRP channels.","method":"Neuron-specific conditional KO and overexpression (AgRP-Cre, POMC-Cre), co-immunoprecipitation for LepR interaction, patch-clamp electrophysiology, body weight measurement, dietary obesity model","journal":"Nature metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional neuron-specific KO and OE, co-IP for LepR binding, electrophysiology for channel mechanism, multiple neuronal populations tested","pmids":["36593271"],"is_preprint":false}],"current_model":"GRB10 is a multi-domain adaptor protein (containing RA, PH, BPS, and SH2 domains) that acts as a context-dependent regulator of receptor tyrosine kinase signaling: it binds activated IR, IGF-1R, RET, ELK, FLT3, BCR-ABL, and other RTKs via its SH2 and BPS domains (the BPS domain acting as a pseudosubstrate inhibitor of IR/IGF-1R kinase activity); it recruits the NEDD4 E3 ubiquitin ligase via a phosphotyrosine-independent SH2–C2 interaction to mediate multiubiquitination and degradation of IGF-IR and IR; it is itself a direct substrate of mTORC1 (phosphorylated at Ser501/503), which stabilizes it and promotes feedback inhibition of PI3K/Akt and ERK-MAPK pathways, while at high mTORC1 activity the phosphorylated GRB10 switches binding from IR to raptor to further suppress mTORC1 in adipose tissue; it is phosphorylated by Src/Fyn on Tyr67 (reducing IR binding) and by Akt on Ser428 (creating a 14-3-3 binding site); in the hypothalamus GRB10 binds the leptin receptor and enhances leptin signaling in AgRP and POMC neurons via KATP and TRP channels; its expression is governed by tissue-specific genomic imprinting controlled by differential DNA methylation, Polycomb-mediated histone H3K27 methylation, CTCF-dependent insulator elements, and brain-specific promoters, with maternal-allele expression in peripheral tissues driving growth suppression and paternal-allele expression in neurons influencing social behavior."},"narrative":{"mechanistic_narrative":"GRB10 is a multi-domain adaptor protein that functions as a context-dependent regulator of receptor tyrosine kinase (RTK) and insulin/IGF signaling, coupling activated receptors to downstream control of growth, metabolism, and receptor turnover [PMID:8621530, PMID:17620412]. Through its SH2 domain and an adjacent BPS domain, GRB10 binds activated receptors including the insulin receptor (IR), IGF-1R, RET, ELK, and FLT3 in a kinase-activity- and phosphotyrosine-dependent manner, with the SH2 and BPS domains engaging the receptor activation loop [PMID:7665556, PMID:8621530, PMID:9506989, PMID:23246379]; structural work shows the SH2 domain dimerizes and is geometrically tuned to recognize the turn-containing dual phosphotyrosines of IR/IGF-1R activation loops [PMID:12551896]. The BPS domain acts as a pseudosubstrate inhibitor, directly suppressing IR and IGF-1R kinase activity without itself binding phosphotyrosine [PMID:11287005], while SH2-domain engagement additionally blocks IRS and Shc access to the receptor and attenuates downstream PI3K/Akt and ERK-MAPK signaling [PMID:12493740, PMID:14615605]. GRB10 also serves as an adaptor bridging the NEDD4 (Nedd4) HECT E3 ubiquitin ligase to IGF-1R and IR via a phosphotyrosine-independent SH2–C2 interface, driving receptor multiubiquitination, internalization, and degradation [PMID:12697834, PMID:18286479, PMID:20980250]. GRB10 is integrated into a feedback circuit as a direct mTORC1 substrate: phosphorylation stabilizes GRB10 and enforces negative feedback on PI3K and ERK pathways, and at high mTORC1 activity phospho-GRB10 switches its binding from IR to raptor to suppress mTORC1 itself [PMID:21659605, PMID:24746805]. Its activity is further tuned by Src/Fyn phosphorylation at Tyr67, which reduces IR binding [PMID:10871840], and by Akt phosphorylation at Ser428, which creates a 14-3-3 binding site [PMID:15722337]. In vivo, GRB10 is an imprinted gene whose maternally expressed peripheral allele restrains fetal growth and negatively regulates insulin sensitivity, muscle mass, and adiposity, while the paternally expressed neuronal allele influences social behavior [PMID:17620412, PMID:17562854, PMID:21270893, PMID:22623587]; in the hypothalamus GRB10 binds the leptin receptor and enhances leptin signaling in AgRP and POMC neurons through KATP and TRP channels [PMID:36593271]. Imprinted, allele-specific expression is controlled by a CTCF-bound intronic insulator that organizes allele-specific chromatin looping [PMID:36108632].","teleology":[{"year":1995,"claim":"Established GRB10 as an SH2-domain adaptor and identified RTKs—rather than the EGF receptor—as its preferred partners, defining its molecular class and pointing to receptor-specific signaling.","evidence":"Expression-library cloning with phospho-EGFR, plus yeast two-hybrid/GST pulldown identifying activation-dependent RET binding","pmids":["7731717","7665556"],"confidence":"Medium","gaps":["Functional consequence of receptor binding not established","Physiological RTK partner remained ambiguous at cloning"]},{"year":1996,"claim":"Defined the insulin and IGF-1 receptors as principal GRB10 targets bound in a ligand- and kinase-activity-dependent manner via the SH2 domain, and linked binding to a functional effect on mitogenesis.","evidence":"Yeast two-hybrid, GST pulldown with purified IR/IGF-IR, phosphopeptide mapping, and SH2-domain microinjection mitogenesis assays in fibroblasts","pmids":["8621530","8776723","8798417"],"confidence":"High","gaps":["Direction of regulation (positive vs negative) unresolved","IRS-independence of the IR C-terminus interaction not mechanistically explained"]},{"year":1997,"claim":"Showed insulin-triggered cytosol-to-membrane translocation and receptor preference (IR over IGF-1R), localizing GRB10 action to the activated receptor at the membrane.","evidence":"Cell fractionation, phosphopeptide binding, and receptor-specific co-IP in defined fibroblast lines","pmids":["9006901","9062339"],"confidence":"Medium","gaps":["Receptor preference context-dependent across cell types","Additional binding regions beyond SH2 not fully mapped"]},{"year":1998,"claim":"Identified the BPS domain as a second activation-loop-dependent binding module and broadened the partner set (GHR/JAK2, Tec, BCR-ABL, Raf-1/MEK1), revealing GRB10 as a multivalent adaptor with both receptor and cytoplasmic-kinase contacts.","evidence":"Domain mapping with IR activation-loop mutagenesis, GST pulldown, yeast two-hybrid, and reporter assays across multiple kinases","pmids":["9506989","9632636","9753425","9747873","9553107"],"confidence":"High","gaps":["Whether BPS directly inhibits kinase activity not yet tested","Physiological relevance of cytoplasmic-kinase interactions unclear"]},{"year":2000,"claim":"Resolved an upstream regulatory input: Src/Fyn phosphorylation of GRB10 Tyr67 reduces IR binding, showing GRB10–receptor affinity is itself tunable by tyrosine phosphorylation.","evidence":"In vitro Src/Fyn kinase assays, Y67G mutagenesis, and co-IP binding assays","pmids":["10871840"],"confidence":"High","gaps":["In vivo stoichiometry of Tyr67 phosphorylation unknown","Physiological trigger for Src/Fyn action on GRB10 not defined"]},{"year":2001,"claim":"Established a direct biochemical mechanism—the BPS domain acts as a pseudosubstrate inhibitor of IR/IGF-1R kinase activity—explaining how GRB10 can dampen receptor signaling.","evidence":"Reconstituted in vitro kinase assays with purified BPS and kinase domains plus phosphopeptide competition","pmids":["11287005"],"confidence":"High","gaps":["Quantitative contribution of BPS inhibition in cells not established","Interplay with SH2-mediated effects not dissected here"]},{"year":2002,"claim":"Defined how GRB10 attenuates IR signaling—by blocking IRS access to the receptor—while also showing context-dependent positive coupling to Akt downstream of other RTKs.","evidence":"Yeast tri-hybrid, phosphorylation time-courses in CHO/IR and adipocytes; Akt complex and kinase assays with c-kit","pmids":["12493740","11809791"],"confidence":"Medium","gaps":["Reconciliation of positive vs negative roles across receptors incomplete","Direct Akt-binding interface not mapped"]},{"year":2003,"claim":"Showed GRB10 controls receptor stability by recruiting Nedd4 to ubiquitinate IGF-1R, and bridged its adaptor functions to MAPK suppression, PI3K coupling, and GIGYF partner recruitment.","evidence":"Reciprocal co-IP, ubiquitination assays with catalytic-mutant Nedd4 and inhibitors, PI3K activity assays, and yeast two-hybrid for GIGYF1/2","pmids":["12697834","12771153","14615605","12783867"],"confidence":"High","gaps":["Whether degradation versus signaling inhibition predominates in vivo unresolved","GIGYF functional role not fully defined"]},{"year":2003,"claim":"Provided the structural basis for IR/IGF-1R selectivity by showing the GRB10 SH2 domain dimerizes and is shaped to recognize dual-phosphotyrosine activation-loop turns.","evidence":"1.65 Å crystal structure plus analytical ultracentrifugation","pmids":["12551896"],"confidence":"High","gaps":["Functional role of SH2 dimerization in cells not tested","Full-length protein architecture not captured"]},{"year":2005,"claim":"Linked Akt-dependent phosphorylation of GRB10 (Ser428) to 14-3-3 recruitment and showed endogenous GRB10 loss enhances IGF signaling partly by limiting phosphatase access to the receptor.","evidence":"Akt in vitro kinase assay with S428 mutagenesis and 14-3-3 co-IP; siRNA knockdown with pervanadate rescue","pmids":["15722337","16037382"],"confidence":"Medium","gaps":["Downstream consequence of 14-3-3 binding on GRB10 function unclear","Identity of the relevant phosphatase not established"]},{"year":2007,"claim":"Demonstrated in vivo that the maternally expressed peripheral Grb10 allele is a physiological negative regulator of growth and insulin sensitivity, validating cell-based inhibitory models.","evidence":"Maternal-allele Grb10 knockout mice with hyperinsulinemic-euglycemic clamps and tissue phosphorylation analysis","pmids":["17620412","17562854"],"confidence":"High","gaps":["Tissue-autonomous contributions not yet separated","Molecular basis of overgrowth distinct from insulin sensitivity unresolved"]},{"year":2010,"claim":"Provided atomic-level mechanism for GRB10 as a degradation adaptor: its SH2 domain binds NEDD4 C2 at non-canonical sites independent of phosphotyrosine and can simultaneously engage IGF1R, explaining bridging.","evidence":"2.0 Å crystal structure of the NEDD4 C2–GRB10 SH2 complex","pmids":["20980250"],"confidence":"High","gaps":["Ternary GRB10–NEDD4–receptor complex not structurally resolved","Regulation of complex assembly in cells not addressed"]},{"year":2011,"claim":"Placed GRB10 in a defining feedback circuit by identifying it as a direct mTORC1 substrate whose phosphorylation stabilizes the protein and inhibits PI3K and ERK-MAPK signaling.","evidence":"Large-scale quantitative phosphoproteomics, mTORC1 kinase assays, rapamycin treatment, and pathway readouts; allele-specific brain expression and behavior via conditional KO","pmids":["21659605","21270893"],"confidence":"High","gaps":["Precise phosphosites integrating signals not yet harmonized across studies","Mechanism linking phosphorylation to stabilization unresolved"]},{"year":2014,"claim":"Defined a phospho-switch in which mTOR phosphorylation at Ser501/503 redirects GRB10 binding from IR to raptor, suppressing mTORC1 and controlling adipose lipolysis and thermogenesis.","evidence":"Phospho-specific mutagenesis, raptor co-IP, fat-specific Grb10 KO with lipolysis/thermogenesis assays and rapamycin rescue","pmids":["24746805"],"confidence":"High","gaps":["Quantitative balance between IR and raptor binding in vivo unclear","Generality of the switch across tissues not established"]},{"year":2018,"claim":"Established tissue-autonomous and inducible roles—muscle-specific GRB10 loss drives hypertrophy and insulin sensitivity, and hepatic GRB10 reactivation by ATF4 under ER stress promotes steatosis.","evidence":"Muscle-specific conditional KO with clamps; liver-specific KO with tunicamycin/HFD and ATF4 promoter analysis","pmids":["29370381","29555819"],"confidence":"Medium","gaps":["Signals dictating tissue-specific reactivation incompletely defined","Crosstalk between metabolic and growth phenotypes unresolved"]},{"year":2022,"claim":"Resolved the epigenetic basis of GRB10 imprinting by showing a paternal CTCF-bound intronic insulator (CBR2.3) governs allele-specific chromatin looping and Grb10-Ddc expression.","evidence":"Polymorphic mice, 4C-seq looping, allele-specific CTCF ChIP, and conditional paternal CBR2.3 deletion with phenotyping","pmids":["36108632"],"confidence":"High","gaps":["Connection between looping changes and GRB10 protein-level functions not traced","Conservation of the insulator in humans not addressed"]},{"year":2023,"claim":"Extended GRB10 function to central energy balance by showing it binds the leptin receptor in hypothalamic neurons and enhances leptin signaling via KATP and TRP channels to promote weight loss.","evidence":"AgRP/POMC-specific conditional KO and overexpression, LepR co-IP, and patch-clamp electrophysiology","pmids":["36593271"],"confidence":"High","gaps":["Molecular mechanism by which GRB10 modulates channel activity unclear","Relationship to GRB10's RTK/mTORC1 functions in neurons not defined"]},{"year":null,"claim":"How GRB10's opposing positive and negative signaling roles, its degradation-adaptor function, and its mTORC1 feedback are integrated and dynamically prioritized within a single cell remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model reconciling pseudosubstrate inhibition, IRS blockade, and Nedd4-mediated degradation","Full-length GRB10 structure and its conformational regulation by phosphorylation unknown","Determinants of context-dependent positive versus negative output not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,20,36,23]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[16,18,41]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[20,33,36]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[6,13]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[13]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[33]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,18,37,41]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[29,30,41]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[20,33,36]}],"complexes":[],"partners":["INSR","IGF1R","NEDD4","AKT1","RAF1","FLT3","GIGYF1","LEPR"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q13322","full_name":"Growth factor receptor-bound protein 10","aliases":["GRB10 adapter protein","Insulin receptor-binding protein Grb-IR"],"length_aa":594,"mass_kda":67.2,"function":"Adapter protein which modulates coupling of a number of cell surface receptor kinases with specific signaling pathways. Binds to, and suppress signals from, activated receptors tyrosine kinases, including the insulin (INSR) and insulin-like growth factor (IGF1R) receptors. The inhibitory effect can be achieved by 2 mechanisms: interference with the signaling pathway and increased receptor degradation. Delays and reduces AKT1 phosphorylation in response to insulin stimulation. Blocks association between INSR and IRS1 and IRS2 and prevents insulin-stimulated IRS1 and IRS2 tyrosine phosphorylation. Recruits NEDD4 to IGF1R, leading to IGF1R ubiquitination, increased internalization and degradation by both the proteasomal and lysosomal pathways. May play a role in mediating insulin-stimulated ubiquitination of INSR, leading to proteasomal degradation. Negatively regulates Wnt signaling by interacting with LRP6 intracellular portion and interfering with the binding of AXIN1 to LRP6. Positive regulator of the KDR/VEGFR-2 signaling pathway. May inhibit NEDD4-mediated degradation of KDR/VEGFR-2","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q13322/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GRB10","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GRB10","total_profiled":1310},"omim":[{"mim_id":"618905","title":"SILVER-RUSSELL SYNDROME 2; SRS2","url":"https://www.omim.org/entry/618905"},{"mim_id":"612064","title":"GRB10-INTERACTING GYF PROTEIN 1; GIGYF1","url":"https://www.omim.org/entry/612064"},{"mim_id":"612003","title":"GRB10-INTERACTING GYF PROTEIN 2; GIGYF2","url":"https://www.omim.org/entry/612003"},{"mim_id":"610317","title":"CORDON-BLEU WH2 REPEAT PROTEIN; COBL","url":"https://www.omim.org/entry/610317"},{"mim_id":"609658","title":"NLR FAMILY, PYRIN DOMAIN-CONTAINING 5; 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chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20980250","citation_count":21,"is_preprint":false},{"pmid":"26390806","id":"PMC_26390806","title":"Placental expression of the insulin receptor binding protein GRB10: Relation to human fetoplacental growth and fetal gender.","date":"2015","source":"Placenta","url":"https://pubmed.ncbi.nlm.nih.gov/26390806","citation_count":21,"is_preprint":false},{"pmid":"29555819","id":"PMC_29555819","title":"De-silencing Grb10 contributes to acute ER stress-induced steatosis in mouse liver.","date":"2018","source":"Journal of molecular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/29555819","citation_count":20,"is_preprint":false},{"pmid":"23106268","id":"PMC_23106268","title":"Lmx1a is an activator of Rgs4 and Grb10 and is responsible for the correct specification of rostral and medial mdDA neurons.","date":"2012","source":"The European journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/23106268","citation_count":20,"is_preprint":false},{"pmid":"22222503","id":"PMC_22222503","title":"Lentivirus shRNA Grb10 targeting the pancreas induces apoptosis and improved glucose tolerance due to decreased plasma glucagon levels.","date":"2012","source":"Diabetologia","url":"https://pubmed.ncbi.nlm.nih.gov/22222503","citation_count":20,"is_preprint":false},{"pmid":"25268761","id":"PMC_25268761","title":"Negative regulation of Grb10 Interacting GYF Protein 2 on insulin-like growth factor-1 receptor signaling pathway caused diabetic mice cognitive impairment.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25268761","citation_count":20,"is_preprint":false},{"pmid":"12514746","id":"PMC_12514746","title":"DDC and COBL, flanking the imprinted GRB10 gene on 7p12, are biallelically expressed.","date":"2002","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/12514746","citation_count":19,"is_preprint":false},{"pmid":"17376403","id":"PMC_17376403","title":"GRB10 binds to LRP6, the Wnt co-receptor and inhibits canonical Wnt signaling pathway.","date":"2007","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/17376403","citation_count":19,"is_preprint":false},{"pmid":"12885405","id":"PMC_12885405","title":"Inhibition of FGF receptor signalling in Xenopus oocytes: differential effect of Grb7, Grb10 and Grb14.","date":"2003","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/12885405","citation_count":19,"is_preprint":false},{"pmid":"18985678","id":"PMC_18985678","title":"Mitogenic roles of Gab1 and Grb10 as direct cellular partners in the regulation of MAP kinase signaling.","date":"2008","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18985678","citation_count":18,"is_preprint":false},{"pmid":"15722337","id":"PMC_15722337","title":"Phosphorylation of grb10 regulates its interaction with 14-3-3.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15722337","citation_count":17,"is_preprint":false},{"pmid":"9881709","id":"PMC_9881709","title":"Genomic structure of the gene for the SH2 and pleckstrin homology domain-containing protein GRB10 and evaluation of its role in Hirschsprung disease.","date":"1998","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/9881709","citation_count":17,"is_preprint":false},{"pmid":"18633161","id":"PMC_18633161","title":"Type 2 diabetes mellitus in a non-obese mouse model induced by Meg1/Grb10 overexpression.","date":"2008","source":"Experimental animals","url":"https://pubmed.ncbi.nlm.nih.gov/18633161","citation_count":17,"is_preprint":false},{"pmid":"23974804","id":"PMC_23974804","title":"Brain-expressed imprinted genes and adult behaviour: the example of Nesp and Grb10.","date":"2013","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/23974804","citation_count":16,"is_preprint":false},{"pmid":"35571247","id":"PMC_35571247","title":"circHtra1/miR-3960/GRB10 Axis Promotes Neuronal Loss and Immune Deficiency in Traumatic Brain Injury.","date":"2022","source":"Oxidative medicine and cellular longevity","url":"https://pubmed.ncbi.nlm.nih.gov/35571247","citation_count":16,"is_preprint":false},{"pmid":"31794259","id":"PMC_31794259","title":"Role of Grb10 in mTORC1-dependent regulation of insulin signaling and action in human skeletal muscle cells.","date":"2019","source":"American journal of physiology. Endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/31794259","citation_count":16,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52410,"output_tokens":13871,"usd":0.182647,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":25890,"output_tokens":5780,"usd":0.136975,"stage2_stop_reason":"end_turn"},"total_usd":0.319622,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"GRB10 was cloned as a new SH2 domain protein by screening expression libraries with the tyrosine-phosphorylated EGF receptor C-terminus. It contains an SH2 domain and a central domain with similarity to a C. elegans gene. At least three forms exist in fibroblasts from alternate translational start sites. GRB10 undergoes serine but not tyrosine phosphorylation after EGF treatment. GRB10 binds poorly to the EGF receptor, suggesting a different binding partner.\",\n      \"method\": \"Expression library screening, co-immunoprecipitation, phosphorylation assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — original cloning paper with multiple methods (library screen, IP, phosphorylation assays), single lab\",\n      \"pmids\": [\"7731717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"GRB10 SH2 domain interacts with the RET receptor tyrosine kinase in a phosphorylation/activation-dependent manner, as demonstrated by yeast two-hybrid screen and GST pulldown. GRB10 is the first identified signaling intermediate for RET.\",\n      \"method\": \"Yeast two-hybrid screen, GST fusion protein pulldown, in vivo co-immunoprecipitation using EGFR/Ret chimera\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus in vitro pulldown plus in vivo co-IP, single lab\",\n      \"pmids\": [\"7665556\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"GRB10 SH2 domain binds the insulin receptor (IR) in an insulin-dependent, kinase-activity-dependent manner. The interaction requires the IR C-terminus, with highest affinity for phosphopeptide containing pTyr-1322. GRB10 does not associate with IRS-1, suggesting an IRS-1-independent function of the IR C-terminus.\",\n      \"method\": \"Yeast two-hybrid, GST fusion protein pulldown with purified IR, co-precipitation from cell extracts, phosphopeptide binding assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified components plus mutagenesis plus cell-based co-IP, replicated across multiple approaches in single study\",\n      \"pmids\": [\"8621530\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"GRB10 SH2 domain interacts with the IGF-I receptor (IGF-IR) in a tyrosine kinase-active, receptor-dependent manner, not requiring juxtamembrane Tyr950. GRB10 co-precipitates with IGF-IR in cell lysates. Microinjection of GRB10 SH2 domain fusion protein inhibited insulin- and IGF-I-stimulated mitogenesis but not EGF-stimulated mitogenesis in fibroblasts.\",\n      \"method\": \"Yeast two-hybrid (interaction trap), Western blotting of yeast extracts, microinjection of GST-SH2 fusion protein, DNA synthesis assay\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus functional microinjection assay, single lab\",\n      \"pmids\": [\"8776723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Ligand-activated ELK receptor tyrosine kinase (Eph family) associates with GRB10 via SH2 domain interaction at ELK phospho-Tyr-929 in vascular endothelial cells. This association is phosphorylation-dependent and occurs in vivo upon LERK-2/Fc stimulation.\",\n      \"method\": \"Yeast two-hybrid screen, site-directed mutagenesis, GST pulldown with phosphorylated recombinant ELK, co-immunoprecipitation from endothelial cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid, mutagenesis, in vitro pulldown and in vivo co-IP, single lab\",\n      \"pmids\": [\"8798570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"GRB10/IR-SV1 SH2 domain interacts specifically in vitro with insulin receptor derived from mammalian cells and with IGF-I receptor. Microinjection of the SH2 domain fusion protein inhibited insulin- and IGF-I-stimulated mitogenesis but not EGF-stimulated mitogenesis in fibroblasts.\",\n      \"method\": \"Yeast two-hybrid, GST fusion protein in vitro binding, microinjection into fibroblasts, DNA synthesis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro binding plus functional microinjection, single lab\",\n      \"pmids\": [\"8798417\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"GRB10 protein translocates from cytosol to membrane upon insulin stimulation, mediated by direct interactions with the insulin receptor via SH2 domain and additional regions. The SH2 domain binds at least two sites in the IR: the kinase activation loop and the juxtamembrane site. GRB10 also binds c-Abl SH3 domain via a conserved site, as well as PDGF and EGF receptors.\",\n      \"method\": \"Cell fractionation, co-immunoprecipitation, synthetic phosphopeptide binding assays, mutated receptor studies\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell fractionation plus phosphopeptide binding plus co-IP, single lab\",\n      \"pmids\": [\"9006901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"GRB10 interacts preferentially with insulin receptor over IGF-I receptor in intact mouse fibroblasts. Hormone-activated IR co-precipitated with three GRB10 isoforms, whereas GRB10 was essentially undetectable in IGF-IR immunoprecipitates under the same conditions.\",\n      \"method\": \"Co-immunoprecipitation from R-IR and R+ cell lines with hormone stimulation\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean receptor-specific co-IP in defined cell lines, single lab\",\n      \"pmids\": [\"9062339\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"GRB10 contains a second novel kinase-activity-dependent binding domain, the BPS domain (between PH and SH2), located in ~50 amino acids. The BPS domain interacts with IR and IGF-IR in a kinase-dependent manner requiring the activation loop phosphotyrosines (Y1150/Y1151). The IR interacts with both BPS and SH2 domains; IGF-IR preferentially with BPS; EGFR preferentially with SH2.\",\n      \"method\": \"Domain mapping, site-directed mutagenesis of IR activation loop (Y1150F/Y1151F), GST pulldown, yeast two-hybrid\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis plus in vitro pulldown with domain mapping, multiple orthogonal methods in single study\",\n      \"pmids\": [\"9506989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"GRB10 SH2 domain interacts with Raf-1 and MEK1 kinases in a phosphotyrosine-independent manner. Interaction with Raf-1 is constitutive; interaction with MEK1 requires insulin treatment and follows MAPK activation. Mutation of MEK1 Thr-386 reduces binding. SH2 domain residues Arg-βB5 and Asp-EF2 are required for binding both receptors and kinases. Overexpression of SH2 domain mutants induces apoptosis reversible by wild-type co-expression.\",\n      \"method\": \"Yeast two-hybrid, random mutagenesis of SH2 domain, site-directed mutagenesis of MEK1, transfection/apoptosis assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid with mutagenesis plus cell-based functional assays, single lab\",\n      \"pmids\": [\"9553107\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"GRB10 interacts with GHR (growth hormone receptor) and JAK2 upon GH stimulation in Huh-7 hepatoma cells. GRB10 inhibits transcription of SRE of c-fos and GH response element 2 of Spi2.1 reporter genes but has no effect on STAT5-dependent reporter genes, placing GRB10 as a downstream inhibitor of GH signaling via JAK2 but independent of STAT5.\",\n      \"method\": \"Phage library screening with phosphorylated GHR cytoplasmic domain, co-immunoprecipitation from Huh-7 cells, co-transfection reporter assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus functional reporter assays, single lab\",\n      \"pmids\": [\"9632636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"GRB10/GrbIR is an in vivo substrate of Tec tyrosine kinase. In HEK293 cells, GRB10 becomes profoundly tyrosine-phosphorylated by Tec but not by Syk, JAK2, or insulin receptor. GRB10 expression suppresses Tec-driven and cytokine-driven activation of the c-fos promoter.\",\n      \"method\": \"Yeast two-hybrid screen, transient expression tyrosine phosphorylation assay in HEK293 cells, reporter gene assay\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo phosphorylation assay with kinase specificity controls plus functional reporter, single lab\",\n      \"pmids\": [\"9753425\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"GRB10 interacts with BCR-ABL in a phosphotyrosine-dependent manner at Bcr sites (aa242-446), distinct from the Grb2 binding site. This interaction is kinase-activation-dependent in vivo. A BCR-ABL mutant lacking GRB10 interaction (Bcr/1-242-Abl) partially reduced IL-3 independence and focus formation, indicating GRB10 interaction is important for BCR-ABL transforming function.\",\n      \"method\": \"Yeast two-hybrid with LexA-BCR-ABL bait, in vitro binding, co-immunoprecipitation from CML cells, functional IL-3 independence and focus formation assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid, in vitro binding, in vivo co-IP and functional transformation assays, single lab\",\n      \"pmids\": [\"9747873\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Endogenous GRB10 localizes predominantly to mitochondria (peripherally associated), as shown by immunofluorescence and subcellular fractionation. Small pools translocate to plasma membrane and actin-rich ruffles after IGF-I or serum treatment. GRB10 co-immunoprecipitates with Raf-1 from mitochondrial fractions, and this interaction is enhanced by UV-induced Raf-1 activation. The GRB10-binding site on Raf-1 co-localizes with the Ras-binding domain.\",\n      \"method\": \"Immunofluorescence microscopy, subcellular fractionation, co-immunoprecipitation from mitochondrial fraction, yeast two-hybrid\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immunofluorescence plus fractionation plus co-IP with functional context, single lab\",\n      \"pmids\": [\"10585452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"GRB10 acts as a positive stimulatory signaling adapter in PDGF-BB-, IGF-I-, and insulin-mediated mitogenesis in normal fibroblasts. PDGF receptor β Y771 is required for GRB10 SH2 domain association. Multiple independent strategies (cDNA overexpression, SH2 domain microinjection, cell-permeable peptides) consistently support a positive mitogenic role distinct from EGF.\",\n      \"method\": \"Ecdysone-regulated overexpression, microinjection, cell-permeable Drosophila antennapedia homeodomain fusion peptides, cell proliferation/DNA synthesis assays, co-immunoprecipitation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — four independent experimental strategies in same lab, though contradicted by other studies\",\n      \"pmids\": [\"10454568\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"GRB10 is phosphorylated on tyrosine (Tyr67) by Src and Fyn kinases but not by the insulin receptor kinase directly. Src/Fyn-mediated phosphorylation negatively regulates GRB10 binding to the IR; a Y67G GRB10 mutant shows higher affinity for IR.\",\n      \"method\": \"In vitro kinase assays with purified Src/Fyn, herbimycin A inhibitor, dominant-negative/constitutively-active Src/Fyn transfection, site-directed mutagenesis (Y67G), co-immunoprecipitation\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay plus mutagenesis plus cell-based functional binding assays with multiple orthogonal methods\",\n      \"pmids\": [\"10871840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"GRB10 BPS domain directly inhibits substrate phosphorylation by activated tyrosine kinase domains of IR and IGF-1R in vitro. Inhibition is dependent on activation-loop phosphorylation but peptide competition shows the BPS domain does not bind phosphotyrosine directly, providing a pseudosubstrate-like inhibition mechanism.\",\n      \"method\": \"In vitro kinase assay with purified recombinant BPS domain and tyrosine kinase domains, phosphopeptide competition experiments\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro with purified recombinant proteins plus competition experiments; establishes direct biochemical mechanism\",\n      \"pmids\": [\"11287005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"GRB10 associates with VEGF receptor KDR (VEGFR-2) in response to VEGF stimulation and positively regulates KDR levels and tyrosine phosphorylation. GRB10 tyrosine phosphorylation in response to VEGF requires an intact SH2 domain and is partially mediated by Src. The positive effect on KDR is independent of GRB10 SH2 domain.\",\n      \"method\": \"Co-immunoprecipitation from HUVEC and 293/KDR cells, GRB10 mutant overexpression, qRT-PCR, MAPK signaling readout\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus domain mutagenesis plus signaling readouts, single lab\",\n      \"pmids\": [\"11494124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"GRB10 inhibits IRS-1/IRS-2 PI3K/Akt signaling by physically blocking IRS access to the IR via its SH2 domain. Overexpression reduced insulin-stimulated IRS-1/2 tyrosine phosphorylation and delayed/reduced Akt phosphorylation. Yeast tri-hybrid assays showed GRB10 blocks IR-IRS association. GRB10 does not affect IR catalytic activity toward Tyr972 or Tyr1158/1162/1163.\",\n      \"method\": \"Overexpression in CHO/IR cells and adipocytes, yeast tri-hybrid assay, phosphorylation time-course, co-immunoprecipitation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast tri-hybrid plus cell-based phosphorylation assays with mutagenesis context, single lab\",\n      \"pmids\": [\"12493740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"GRB10 forms a constitutive complex with Akt, and GRB10 co-expression with c-kit synergistically activates Akt in a wortmannin-sensitive, PI3K-independent manner downstream of PI3K. GRB10 is recruited to c-kit via SH2 domain in a phosphotyrosine-dependent manner. Both SH2 and PH domains of GRB10 are required for Akt activation.\",\n      \"method\": \"Yeast two-hybrid screen with c-kit cytoplasmic domain, co-immunoprecipitation, Akt kinase assay, dominant-negative/deletion mutants, wortmannin inhibition, Ba/F3 IL-3 independence assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus kinase assay plus functional IL-3 independence, multiple methods single lab\",\n      \"pmids\": [\"11809791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"GRB10 forms a complex with Nedd4 E3 ubiquitin ligase and IGF-IR. GRB10 promotes ligand-dependent ubiquitination and accelerated internalization and degradation of IGF-IR via both proteasomal and lysosomal pathways. Catalytically inactive Nedd4-CS mutant or GRB10 mutant lacking SH2 domain both impair IGF-IR ubiquitination. GRB10 acts as an adapter bridging Nedd4 to IGF-IR.\",\n      \"method\": \"Co-immunoprecipitation, overexpression in mouse embryo fibroblasts, ubiquitination assay, receptor half-life measurement, inhibitors MG132 and chloroquine, dansylcadaverine treatment, Nedd4-CS catalytic mutant\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, ubiquitination assay with catalytic mutant controls, multiple inhibitor approaches, replicated with domain mutant; first demonstration of HECT E3 regulation of RTK stability\",\n      \"pmids\": [\"12697834\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"GRB10 N-terminus interacts with two novel proteins, GIGYF1 and GIGYF2, via GYF domain binding to tandem proline-rich regions. In IGF-I-stimulated cells, GIGYF1 binding to GRB10 increases, and both transiently associate with IGF-IR, with GIGYF1 later dissociating while GRB10 remains. Overexpression of GRB10-binding GIGYF1 fragment increases IGF-I-stimulated receptor tyrosine phosphorylation.\",\n      \"method\": \"Yeast two-hybrid screen with GRB10 N-terminus bait, mutation analysis, co-immunoprecipitation from R+ fibroblasts, overexpression assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus cell-based co-IP plus functional overexpression, single lab\",\n      \"pmids\": [\"12771153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"GRB10 negatively regulates insulin-stimulated MAPK signaling by inhibiting Shc tyrosine phosphorylation in an SH2 domain-dependent manner. Overexpression reduced insulin-stimulated MAPK/Elk1 phosphorylation; RNAi knockdown enhanced MAPK, Shc, and Akt phosphorylation.\",\n      \"method\": \"Overexpression in CHO/IR cells and adipocytes, RNA interference in HeLa/IR cells, phosphorylation assays, SH2-deletion mutant\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain- and loss-of-function with domain mutant, single lab\",\n      \"pmids\": [\"14615605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"GRB10 functions as a critical component of the IR signaling complex linking IR to p85 PI3K, regulating PI3K activity and metabolic insulin responses (glycogen synthesis, glucose and amino acid transport, lipogenesis). Direct association between GRB10 and p85 was demonstrated; no association between GRB10 and IRS proteins was detected. Dominant-negative GRB10 SH2 domain and Pro-rich region abolished metabolic insulin response in 3T3-L1 adipocytes.\",\n      \"method\": \"Co-immunoprecipitation, PI3K activity assay, dominant-negative domain expression, metabolic assays in 3T3-L1 adipocytes and L6 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, kinase activity assay, functional metabolic readouts, single lab\",\n      \"pmids\": [\"12783867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The GRB10 SH2 domain forms a non-covalent dimer in solution under physiologic conditions. Crystal structure at 1.65 Å resolution reveals a dimer interface involving residues in/flanking the C-terminal alpha helix conserved in Grb7/10/14. Val-522 (BG loop) and Asp-500 (EF loop) position interferes with P+3 phosphopeptide binding, favoring dimeric turn-containing phosphotyrosine sequences such as IR/IGF-1R activation loops.\",\n      \"method\": \"X-ray crystallography (1.65 Å), analytical ultracentrifugation for dimerization in solution\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus solution biophysics, clear structural basis for ligand specificity\",\n      \"pmids\": [\"12551896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"GRB10 prevents Nedd4-mediated degradation of VEGF-R2. GRB10 constitutively associates with Nedd4. Co-expression of GRB10 and Nedd4 restores VEGF-R2 expression that is otherwise reduced by Nedd4. Nedd4 itself does not directly ubiquitinate VEGF-R2 (Nedd4C854S ligase-dead mutant retains VEGF-R2 ubiquitination). Thus GRB10 acts as a positive regulator protecting VEGF-R2 from Nedd4-mediated degradation.\",\n      \"method\": \"Co-immunoprecipitation, overexpression of Nedd4 and GRB10 in cells, Nedd4-CS catalytic mutant, MG132 proteasome inhibitor, ubiquitination assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus functional assays with catalytic mutant control, single lab\",\n      \"pmids\": [\"15060076\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Endogenous GRB10 knockdown by siRNA enhances IGF-I-mediated phosphorylation of IRS proteins, Akt, and ERK1/2 and increases DNA synthesis. Knockdown also decreases IGF-I-stimulated receptor autophosphorylation, partially reversed by pervanadate (phosphatase inhibitor), indicating GRB10 blocks phosphatase access to the activated IGF-IR. GIGYF proteins interact specifically with GRB10 but not Grb7 or Grb14.\",\n      \"method\": \"siRNA knockdown, phosphorylation assays, DNA synthesis assay, pervanadate treatment, yeast two-hybrid specificity assays\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA loss-of-function with multiple signaling readouts and pharmacological evidence for mechanism, single lab\",\n      \"pmids\": [\"16037382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"GRB10 N-terminal domains (absent in BPS-SH2 fragment) are required for effects on IR autophosphorylation and glucose uptake in 3T3-L1 adipocytes. Full-length GRB10 inhibits IR autophosphorylation and glucose uptake, while BPS-SH2 fragment inhibits post-receptor signaling (IRS1, IRS2, Akt, Shc, ERK, APS, c-Cbl) but not receptor phosphorylation or glucose uptake despite more sustained IR binding.\",\n      \"method\": \"Overexpression of full-length vs. truncated GRB10, glucose uptake assay, phosphorylation assays, co-precipitation\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain deletion analysis with multiple functional and biochemical readouts, single lab\",\n      \"pmids\": [\"15664450\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"GRB10 mediates insulin-stimulated ubiquitination and proteasomal degradation of the insulin receptor. Suppression of endogenous GRB10 increased IR protein levels without affecting IR mRNA, and blocked insulin-induced IR ubiquitination and reduction. Overexpression of GRB10 reduced IR protein levels. MG132 (proteasomal inhibitor) but not chloroquine (lysosomal inhibitor) reversed IR reduction.\",\n      \"method\": \"Stable overexpression and RNAi knockdown cell lines, mRNA/protein level analysis, ubiquitination assay, MG132 and chloroquine treatment\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — bidirectional gain/loss of function with mechanistic dissection using inhibitors, single lab\",\n      \"pmids\": [\"16434550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Peripheral disruption of Grb10 (maternal allele) in mice leads to overgrowth and enhanced insulin-stimulated Akt and MAPK phosphorylation in skeletal muscle and fat. Hyperinsulinemic-euglycemic clamp studies revealed increased insulin sensitivity in peripheral tissues, establishing GRB10 as a negative regulator of insulin signaling and action in vivo.\",\n      \"method\": \"Gene trap knockout mice (maternal allele), hyperinsulinemic-euglycemic clamp, phosphorylation assays in tissues\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic KO with gold-standard clamp studies and tissue signaling, replicated across multiple insulin target tissues\",\n      \"pmids\": [\"17620412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Adult Grb10Δ2-4 knockout mice show improved glucose tolerance, insulin sensitivity, increased muscle mass, and reduced adiposity. Tissue-specific IR tyrosine phosphorylation changes are consistent with GRB10 preventing phosphatases from accessing IR activation-loop phosphotyrosines. Insulin-induced IRS-1 phosphorylation is enhanced, supporting GRB10 attenuation of IR-to-IRS-1 signal transmission.\",\n      \"method\": \"Grb10 gene disruption mouse model, glucose tolerance and insulin tolerance tests, IR/IRS-1 phosphorylation assays, body composition analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO model with multiple metabolic and biochemical endpoints; mechanistic model supported by phosphorylation pattern\",\n      \"pmids\": [\"17562854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Phosphorylation of GRB10 serine 428 by Akt creates a binding site for 14-3-3 proteins. Mutation of Ser428 diminishes 14-3-3 binding. Akt directly binds GRB10 constitutively and phosphorylates GRB10 on Ser428 in an in vitro kinase assay.\",\n      \"method\": \"Yeast two-hybrid screen for 14-3-3 interaction, site-directed mutagenesis (S428), co-immunoprecipitation, in vitro Akt kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay plus mutagenesis plus co-IP, single lab\",\n      \"pmids\": [\"15722337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"GRB10 and active Raf-1 promote Bad-dependent cell survival. Both GRB10-deficient and Raf-1-deficient MEFs show enhanced apoptosis upon Bad expression. GRB10 SH2, PH, and proline-rich domains plus Akt phosphorylation site and 14-3-3 binding are required for anti-apoptotic function. Raf-1 kinase activity, Src phosphorylation (Tyr340/341), and Ras-binding domain interaction with GRB10 SH2 are required. GRB10 and Raf-1 are required for PI3K/Akt and MAPK pathways to phosphorylate and inactivate Bad.\",\n      \"method\": \"KO MEFs from Grb10 and Raf-1 knockout mice, Bad overexpression apoptosis assay, structure-function analysis with domain mutants, siRNA, signaling inhibitor studies, mutagenesis of Bad phosphorylation sites\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO cells plus domain mutagenesis plus siRNA, multiple orthogonal approaches, single lab\",\n      \"pmids\": [\"17535812\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The GRB10/Nedd4 complex mediates multiubiquitination (not polyubiquitination) of IGF-IR upon ligand stimulation, which is required for receptor internalization via both clathrin-dependent and -independent pathways. GRB10 and Nedd4 remain associated with IGF-IR in early endosomes and caveosomes and are not degraded themselves, potentially being directed to recycling endosomes.\",\n      \"method\": \"Ubiquitination assays with K48R/K63R ubiquitin mutants, internalization assays, subcellular fractionation, co-immunoprecipitation from endosomes\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitin mutant assays plus fractionation plus co-IP, single lab\",\n      \"pmids\": [\"18286479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of GRB10 RA and PH domains at 2.6 Å reveals these domains and the intervening linker form an integrated, dimeric structural unit. Biochemical studies showed Grb14 binds activated Ras, suggesting Ras binding may serve as a timing mechanism for downregulation of insulin signaling. Results illuminate membrane-recruitment mechanisms of GRB7/10/14 family and related actin-cytoskeleton proteins.\",\n      \"method\": \"X-ray crystallography (2.6 Å resolution), biochemical Ras binding assays\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus biochemical validation, rigorous structural study\",\n      \"pmids\": [\"19648926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"GRB10 knockdown in human pancreatic islets reduces insulin and glucagon secretion, suggesting GRB10 plays a role in islet function beyond its known role in insulin signaling.\",\n      \"method\": \"siRNA knockdown in human pancreatic islets, insulin and glucagon secretion assays\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown in primary human islets with functional secretion readout, single study\",\n      \"pmids\": [\"24699409\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Crystal structure of NEDD4 C2 domain – GRB10 SH2 complex at 2.0 Å reveals three interaction interfaces. Main interface is an antiparallel β-sheet between GRB10 SH2 F-strand and NEDD4 C2 C-strand. NEDD4 C2 binds at non-classical sites far from the phosphotyrosine-binding pocket, making the interaction phosphotyrosine-independent. GRB10 SH2 can simultaneously bind NEDD4 C2 and IGF1R kinase domain.\",\n      \"method\": \"X-ray crystallography (2.0 Å), structural analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure providing atomic-level mechanism for GRB10 as adapter bridging NEDD4 to IGF1R\",\n      \"pmids\": [\"20980250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"GRB10 is a direct substrate of mTORC1. mTORC1-mediated phosphorylation stabilizes GRB10 protein. Phosphorylated GRB10 acts as a feedback inhibitor of the PI3K and ERK-MAPK pathways. Identified by large-scale quantitative phosphoproteomics.\",\n      \"method\": \"Quantitative phosphoproteomics (large-scale), mTORC1 kinase assay, rapamycin treatment, GRB10 stability assays, pathway readouts\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — phosphoproteomics discovery plus kinase substrate validation plus functional pathway inhibition, replicated across multiple cell systems\",\n      \"pmids\": [\"21659605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Within the brain, Grb10 is expressed from the paternal allele (not maternal as in peripheral tissues), and ablation of paternal Grb10 increases social dominance and allogrooming behavior. Loss of the peripherally-expressed maternal allele causes fetal and placental overgrowth. Thus the two parental alleles function in different tissues to influence distinct physiological processes.\",\n      \"method\": \"Conditional knockout mice (paternal vs maternal allele ablation), behavioral testing, body weight/placental weight measurement\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — allele-specific conditional KO with well-characterized behavioral and physiological phenotypes, published in high-impact journal with rigorous controls\",\n      \"pmids\": [\"21270893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"GRB10 deletion in mice increases myofiber number (not myofiber size) by 142% in skeletal muscle, with increased muscle mass maintained through 12 months. The hypermuscularity arises during embryonic development. Neonatal Grb10-deficient hindlimbs show increased functional gene signatures for myogenic signaling and proliferation.\",\n      \"method\": \"Grb10 knockout mice, histomorphometry (fiber number/size), gene expression profiling, neonatal tissue analysis\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with quantitative histomorphometry and gene expression, single lab\",\n      \"pmids\": [\"22623587\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"GRB10 physically associates with FLT3 via FLT3 phospho-Tyr572 and Tyr793 in response to FLT3-ligand stimulation, and constitutively with oncogenic FLT3-ITD. GRB10 enhances FL-induced Akt phosphorylation by direct interaction with p85 PI3K subunit downstream of FLT3. GRB10 expression increases STAT5 activation in FLT3-ITD cells and promotes S-phase progression and survival.\",\n      \"method\": \"Co-immunoprecipitation (endogenous and overexpressed), phospho-mutant FLT3 constructs, Akt/ERK/p38 phosphorylation assays, siRNA knockdown, p85 interaction studies, cell cycle analysis\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with phospho-mutants plus downstream signaling, single lab\",\n      \"pmids\": [\"23246379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"mTOR-mediated phosphorylation of GRB10 at Ser501/503 switches its binding preference from the insulin receptor to raptor (mTORC1 component), leading to dissociation of raptor from mTOR and downregulation of mTORC1 signaling as a feedback mechanism. Fat-specific disruption of GRB10 increased mTORC1 signaling in adipose tissue, suppressed lipolysis, and reduced thermogenic function, effects reversed by rapamycin.\",\n      \"method\": \"mTOR phosphorylation assays, phospho-specific mutagenesis (S501/503), raptor co-immunoprecipitation, fat-specific Grb10 KO mice, lipolysis assay, thermogenesis measurement, rapamycin rescue\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — phospho-mutagenesis plus co-IP plus in vivo KO with rapamycin rescue, multiple orthogonal methods establishing feedback mechanism\",\n      \"pmids\": [\"24746805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"GRB10 binds to the intracellular portion of LRP6, the Wnt co-receptor, and negatively regulates Wnt signaling. GRB10 overexpression suppressed Wnt3a- and LRP6-induced TCF-dependent reporter activity upstream of β-catenin. RNAi knockdown of GRB10 enhanced Wnt3a-induced reporter activity. GRB10 interferes with Axin binding to LRP6 as the proposed mechanism.\",\n      \"method\": \"Co-immunoprecipitation, TCF reporter assays, RNAi knockdown, β-catenin accumulation assay, Axin binding competition\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus gain/loss-of-function reporter assays plus mechanistic Axin competition, single lab\",\n      \"pmids\": [\"17376403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In mouse embryonic fibroblasts, GRB10 and Raf-1 form a complex that co-immunoprecipitates from mitochondrial fractions. GRB10 interacts with MEK1 in an insulin-dependent manner following MAPK activation. Direct GRB10-Gab1 association occurs in a peptide hormone-dependent manner via GRB10 SH2 domain binding to the Crk-binding region of Gab1, and elevated GRB10 potentiates MAPK-dependent mitogenesis in a Gab1-dependent manner.\",\n      \"method\": \"Peptide hormone-dependent co-immunoprecipitation, GRB10 SH2 domain peptide mimetic competition, Gab1 gene disruption cell lines, MAPK inhibitor studies, cell proliferation assays\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus KO cells plus inhibitor studies, single lab\",\n      \"pmids\": [\"18985678\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"GRB10 adapter protein decreases total Kv1.3 potassium channel expression, particularly at the membrane surface, and eliminates BDNF-induced phosphorylation of Kv1.3 via interaction with basally phosphorylated Tyr111-113 and Tyr449 residues on the channel. Negative regulation by GRB10 prevents BDNF-induced current suppression of Kv1.3. GRB10 does not directly complex with Kv1.3 in HEK293 cells but co-immunoprecipitates with Kv1.3 in native olfactory bulb.\",\n      \"method\": \"Immunocytochemistry, co-immunoprecipitation from HEK293 and native olfactory bulb, Kv1.3 point mutations (tyrosine to phenylalanine), patch-clamp electrophysiology, Western blot for expression levels\",\n      \"journal\": \"BMC neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis plus electrophysiology plus co-IP, single lab\",\n      \"pmids\": [\"19166614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"GRB10 is activated downstream of TORC1 upon IL-4 stimulation in macrophages, associates with IRS-2, NEDD4.2, IL-4Rα and γC, and its knockdown enhances tyrosine phosphorylation of IRS-2 and M2 gene expression. IL-4Rα and γC are ubiquitinated after IL-4 stimulation, suggesting GRB10 regulates IL-4 receptor-signaling complex degradation through interactions with NEDD4.2.\",\n      \"method\": \"siRNA knockdown, co-immunoprecipitation, phosphorylation assays, M2 gene expression assays, ubiquitination assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA KD plus co-IP plus ubiquitination readout, single lab\",\n      \"pmids\": [\"27742835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"GRB10 deletion (maternal allele) substantially increases HSC long-term repopulating capacity and accelerates HSC regeneration after total body irradiation. GRB10-deficient HSCs show increased proliferation with upregulation of CDK4 and Cyclin E. Enhanced HSC regeneration is dependent on activation of the Akt/mTORC1 pathway.\",\n      \"method\": \"Grb10 maternal allele KO mice, competitive transplantation assay, total body irradiation reconstitution, CDK4/Cyclin E expression analysis, rapamycin treatment to test mTORC1 dependence\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo transplantation plus rapamycin rescue establishing pathway dependence, single lab\",\n      \"pmids\": [\"27806297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Ablation of GRB10 specifically in muscle (using α-skeletal actin-Cre) is sufficient to cause muscle enlargement (increased fiber cross-sectional area) and increased insulin-stimulated glucose uptake with enhanced phospho-Akt in muscle. This confirms a muscle-autonomous role for GRB10 in growth and proximal insulin receptor signaling.\",\n      \"method\": \"Muscle-specific Cre-lox conditional KO (Grb10-mKO), hyperinsulinemic-euglycemic clamp, phospho-Akt assay in muscle\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific conditional KO with clamp studies establishing cell-autonomous role, single lab\",\n      \"pmids\": [\"29370381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The Grb10 gene is silenced in adult mouse liver but can be reactivated by acute ER stress (tunicamycin or short-term high-fat diet) via ATF4-mediated transcriptional upregulation. Reactivated GRB10 promotes hepatic lipid dysregulation and steatosis; liver-specific GRB10 KO suppresses lipogenic gene expression and acute ER stress-induced hepatosteatosis.\",\n      \"method\": \"Liver-specific KO mice, tunicamycin/HFD challenge, ATF4 identification by luciferase reporter and ChIP/promoter analysis, hepatic lipid/gene expression assays\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — liver-specific KO plus transcriptional mechanism identification, single lab\",\n      \"pmids\": [\"29555819\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GRB10 knockdown in human primary skeletal muscle myotubes enhances insulin-induced PI3K/Akt signaling and glucose uptake associated with increased insulin receptor abundance. mTORC1-mediated phosphorylation of GRB10 at Ser476 is stimulated by both insulin and amino acids independently and additively; rapamycin blocks this phosphorylation and disrupts negative feedback on PI3K/Akt, suggesting mTORC1 controls insulin receptor abundance via GRB10.\",\n      \"method\": \"siRNA knockdown in human primary myotubes, Ser476 phosphorylation assay, rapamycin treatment, glucose uptake assay, insulin receptor abundance measurement\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA KD in primary human cells plus phosphorylation assays with mTORC1 inhibitor, single lab\",\n      \"pmids\": [\"31794259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"An intronic secondary differentially methylated region (CBR2.3) within Grb10 on the paternal chromosome has tissue-specific paternal CTCF binding that functions as an insulator controlling allele-specific chromatin looping contacts with the neighboring Ddc gene. Deletion of paternal CBR2.3 removes this insulator, shifts chromatin looping, creates ectopic enhancer-promoter contacts, and destabilizes normal Grb10-Ddc allele-specific expression with developmental consequences in heart and muscle.\",\n      \"method\": \"Polymorphic mice, 4C-seq chromatin looping, allele-specific CTCF ChIP, conditional paternal CBR2.3 deletion, expression analysis, cardiac/muscle phenotyping\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — genetic deletion plus 3D chromatin mapping plus allele-specific expression in vivo, multiple orthogonal approaches\",\n      \"pmids\": [\"36108632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"GRB10 in hypothalamic AgRP and POMC neurons enhances leptin signaling and promotes weight loss. GRB10 interacts with the leptin receptor (LepR) in hypothalamic neurons. Ablation of GRB10 in AgRP neurons promotes weight gain; overexpression reduces body weight. GRB10 exaggerates inhibitory effects of leptin on AgRP neurons via ATP-sensitive potassium channel (KATP) currents and facilitates leptin's excitatory drive on POMC neurons via TRP channels.\",\n      \"method\": \"Neuron-specific conditional KO and overexpression (AgRP-Cre, POMC-Cre), co-immunoprecipitation for LepR interaction, patch-clamp electrophysiology, body weight measurement, dietary obesity model\",\n      \"journal\": \"Nature metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional neuron-specific KO and OE, co-IP for LepR binding, electrophysiology for channel mechanism, multiple neuronal populations tested\",\n      \"pmids\": [\"36593271\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GRB10 is a multi-domain adaptor protein (containing RA, PH, BPS, and SH2 domains) that acts as a context-dependent regulator of receptor tyrosine kinase signaling: it binds activated IR, IGF-1R, RET, ELK, FLT3, BCR-ABL, and other RTKs via its SH2 and BPS domains (the BPS domain acting as a pseudosubstrate inhibitor of IR/IGF-1R kinase activity); it recruits the NEDD4 E3 ubiquitin ligase via a phosphotyrosine-independent SH2–C2 interaction to mediate multiubiquitination and degradation of IGF-IR and IR; it is itself a direct substrate of mTORC1 (phosphorylated at Ser501/503), which stabilizes it and promotes feedback inhibition of PI3K/Akt and ERK-MAPK pathways, while at high mTORC1 activity the phosphorylated GRB10 switches binding from IR to raptor to further suppress mTORC1 in adipose tissue; it is phosphorylated by Src/Fyn on Tyr67 (reducing IR binding) and by Akt on Ser428 (creating a 14-3-3 binding site); in the hypothalamus GRB10 binds the leptin receptor and enhances leptin signaling in AgRP and POMC neurons via KATP and TRP channels; its expression is governed by tissue-specific genomic imprinting controlled by differential DNA methylation, Polycomb-mediated histone H3K27 methylation, CTCF-dependent insulator elements, and brain-specific promoters, with maternal-allele expression in peripheral tissues driving growth suppression and paternal-allele expression in neurons influencing social behavior.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GRB10 is a multi-domain adaptor protein that functions as a context-dependent regulator of receptor tyrosine kinase (RTK) and insulin/IGF signaling, coupling activated receptors to downstream control of growth, metabolism, and receptor turnover [#2, #29]. Through its SH2 domain and an adjacent BPS domain, GRB10 binds activated receptors including the insulin receptor (IR), IGF-1R, RET, ELK, and FLT3 in a kinase-activity- and phosphotyrosine-dependent manner, with the SH2 and BPS domains engaging the receptor activation loop [#1, #2, #8, #40]; structural work shows the SH2 domain dimerizes and is geometrically tuned to recognize the turn-containing dual phosphotyrosines of IR/IGF-1R activation loops [#24]. The BPS domain acts as a pseudosubstrate inhibitor, directly suppressing IR and IGF-1R kinase activity without itself binding phosphotyrosine [#16], while SH2-domain engagement additionally blocks IRS and Shc access to the receptor and attenuates downstream PI3K/Akt and ERK-MAPK signaling [#18, #22]. GRB10 also serves as an adaptor bridging the NEDD4 (Nedd4) HECT E3 ubiquitin ligase to IGF-1R and IR via a phosphotyrosine-independent SH2–C2 interface, driving receptor multiubiquitination, internalization, and degradation [#20, #33, #36]. GRB10 is integrated into a feedback circuit as a direct mTORC1 substrate: phosphorylation stabilizes GRB10 and enforces negative feedback on PI3K and ERK pathways, and at high mTORC1 activity phospho-GRB10 switches its binding from IR to raptor to suppress mTORC1 itself [#37, #41]. Its activity is further tuned by Src/Fyn phosphorylation at Tyr67, which reduces IR binding [#15], and by Akt phosphorylation at Ser428, which creates a 14-3-3 binding site [#31]. In vivo, GRB10 is an imprinted gene whose maternally expressed peripheral allele restrains fetal growth and negatively regulates insulin sensitivity, muscle mass, and adiposity, while the paternally expressed neuronal allele influences social behavior [#29, #30, #38, #39]; in the hypothalamus GRB10 binds the leptin receptor and enhances leptin signaling in AgRP and POMC neurons through KATP and TRP channels [#51]. Imprinted, allele-specific expression is controlled by a CTCF-bound intronic insulator that organizes allele-specific chromatin looping [#50].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established GRB10 as an SH2-domain adaptor and identified RTKs—rather than the EGF receptor—as its preferred partners, defining its molecular class and pointing to receptor-specific signaling.\",\n      \"evidence\": \"Expression-library cloning with phospho-EGFR, plus yeast two-hybrid/GST pulldown identifying activation-dependent RET binding\",\n      \"pmids\": [\"7731717\", \"7665556\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of receptor binding not established\", \"Physiological RTK partner remained ambiguous at cloning\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Defined the insulin and IGF-1 receptors as principal GRB10 targets bound in a ligand- and kinase-activity-dependent manner via the SH2 domain, and linked binding to a functional effect on mitogenesis.\",\n      \"evidence\": \"Yeast two-hybrid, GST pulldown with purified IR/IGF-IR, phosphopeptide mapping, and SH2-domain microinjection mitogenesis assays in fibroblasts\",\n      \"pmids\": [\"8621530\", \"8776723\", \"8798417\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direction of regulation (positive vs negative) unresolved\", \"IRS-independence of the IR C-terminus interaction not mechanistically explained\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Showed insulin-triggered cytosol-to-membrane translocation and receptor preference (IR over IGF-1R), localizing GRB10 action to the activated receptor at the membrane.\",\n      \"evidence\": \"Cell fractionation, phosphopeptide binding, and receptor-specific co-IP in defined fibroblast lines\",\n      \"pmids\": [\"9006901\", \"9062339\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor preference context-dependent across cell types\", \"Additional binding regions beyond SH2 not fully mapped\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identified the BPS domain as a second activation-loop-dependent binding module and broadened the partner set (GHR/JAK2, Tec, BCR-ABL, Raf-1/MEK1), revealing GRB10 as a multivalent adaptor with both receptor and cytoplasmic-kinase contacts.\",\n      \"evidence\": \"Domain mapping with IR activation-loop mutagenesis, GST pulldown, yeast two-hybrid, and reporter assays across multiple kinases\",\n      \"pmids\": [\"9506989\", \"9632636\", \"9753425\", \"9747873\", \"9553107\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether BPS directly inhibits kinase activity not yet tested\", \"Physiological relevance of cytoplasmic-kinase interactions unclear\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Resolved an upstream regulatory input: Src/Fyn phosphorylation of GRB10 Tyr67 reduces IR binding, showing GRB10–receptor affinity is itself tunable by tyrosine phosphorylation.\",\n      \"evidence\": \"In vitro Src/Fyn kinase assays, Y67G mutagenesis, and co-IP binding assays\",\n      \"pmids\": [\"10871840\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo stoichiometry of Tyr67 phosphorylation unknown\", \"Physiological trigger for Src/Fyn action on GRB10 not defined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Established a direct biochemical mechanism—the BPS domain acts as a pseudosubstrate inhibitor of IR/IGF-1R kinase activity—explaining how GRB10 can dampen receptor signaling.\",\n      \"evidence\": \"Reconstituted in vitro kinase assays with purified BPS and kinase domains plus phosphopeptide competition\",\n      \"pmids\": [\"11287005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution of BPS inhibition in cells not established\", \"Interplay with SH2-mediated effects not dissected here\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined how GRB10 attenuates IR signaling—by blocking IRS access to the receptor—while also showing context-dependent positive coupling to Akt downstream of other RTKs.\",\n      \"evidence\": \"Yeast tri-hybrid, phosphorylation time-courses in CHO/IR and adipocytes; Akt complex and kinase assays with c-kit\",\n      \"pmids\": [\"12493740\", \"11809791\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation of positive vs negative roles across receptors incomplete\", \"Direct Akt-binding interface not mapped\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed GRB10 controls receptor stability by recruiting Nedd4 to ubiquitinate IGF-1R, and bridged its adaptor functions to MAPK suppression, PI3K coupling, and GIGYF partner recruitment.\",\n      \"evidence\": \"Reciprocal co-IP, ubiquitination assays with catalytic-mutant Nedd4 and inhibitors, PI3K activity assays, and yeast two-hybrid for GIGYF1/2\",\n      \"pmids\": [\"12697834\", \"12771153\", \"14615605\", \"12783867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether degradation versus signaling inhibition predominates in vivo unresolved\", \"GIGYF functional role not fully defined\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Provided the structural basis for IR/IGF-1R selectivity by showing the GRB10 SH2 domain dimerizes and is shaped to recognize dual-phosphotyrosine activation-loop turns.\",\n      \"evidence\": \"1.65 Å crystal structure plus analytical ultracentrifugation\",\n      \"pmids\": [\"12551896\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of SH2 dimerization in cells not tested\", \"Full-length protein architecture not captured\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Linked Akt-dependent phosphorylation of GRB10 (Ser428) to 14-3-3 recruitment and showed endogenous GRB10 loss enhances IGF signaling partly by limiting phosphatase access to the receptor.\",\n      \"evidence\": \"Akt in vitro kinase assay with S428 mutagenesis and 14-3-3 co-IP; siRNA knockdown with pervanadate rescue\",\n      \"pmids\": [\"15722337\", \"16037382\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream consequence of 14-3-3 binding on GRB10 function unclear\", \"Identity of the relevant phosphatase not established\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated in vivo that the maternally expressed peripheral Grb10 allele is a physiological negative regulator of growth and insulin sensitivity, validating cell-based inhibitory models.\",\n      \"evidence\": \"Maternal-allele Grb10 knockout mice with hyperinsulinemic-euglycemic clamps and tissue phosphorylation analysis\",\n      \"pmids\": [\"17620412\", \"17562854\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-autonomous contributions not yet separated\", \"Molecular basis of overgrowth distinct from insulin sensitivity unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Provided atomic-level mechanism for GRB10 as a degradation adaptor: its SH2 domain binds NEDD4 C2 at non-canonical sites independent of phosphotyrosine and can simultaneously engage IGF1R, explaining bridging.\",\n      \"evidence\": \"2.0 Å crystal structure of the NEDD4 C2–GRB10 SH2 complex\",\n      \"pmids\": [\"20980250\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ternary GRB10–NEDD4–receptor complex not structurally resolved\", \"Regulation of complex assembly in cells not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed GRB10 in a defining feedback circuit by identifying it as a direct mTORC1 substrate whose phosphorylation stabilizes the protein and inhibits PI3K and ERK-MAPK signaling.\",\n      \"evidence\": \"Large-scale quantitative phosphoproteomics, mTORC1 kinase assays, rapamycin treatment, and pathway readouts; allele-specific brain expression and behavior via conditional KO\",\n      \"pmids\": [\"21659605\", \"21270893\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise phosphosites integrating signals not yet harmonized across studies\", \"Mechanism linking phosphorylation to stabilization unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined a phospho-switch in which mTOR phosphorylation at Ser501/503 redirects GRB10 binding from IR to raptor, suppressing mTORC1 and controlling adipose lipolysis and thermogenesis.\",\n      \"evidence\": \"Phospho-specific mutagenesis, raptor co-IP, fat-specific Grb10 KO with lipolysis/thermogenesis assays and rapamycin rescue\",\n      \"pmids\": [\"24746805\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative balance between IR and raptor binding in vivo unclear\", \"Generality of the switch across tissues not established\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established tissue-autonomous and inducible roles—muscle-specific GRB10 loss drives hypertrophy and insulin sensitivity, and hepatic GRB10 reactivation by ATF4 under ER stress promotes steatosis.\",\n      \"evidence\": \"Muscle-specific conditional KO with clamps; liver-specific KO with tunicamycin/HFD and ATF4 promoter analysis\",\n      \"pmids\": [\"29370381\", \"29555819\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signals dictating tissue-specific reactivation incompletely defined\", \"Crosstalk between metabolic and growth phenotypes unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved the epigenetic basis of GRB10 imprinting by showing a paternal CTCF-bound intronic insulator (CBR2.3) governs allele-specific chromatin looping and Grb10-Ddc expression.\",\n      \"evidence\": \"Polymorphic mice, 4C-seq looping, allele-specific CTCF ChIP, and conditional paternal CBR2.3 deletion with phenotyping\",\n      \"pmids\": [\"36108632\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Connection between looping changes and GRB10 protein-level functions not traced\", \"Conservation of the insulator in humans not addressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended GRB10 function to central energy balance by showing it binds the leptin receptor in hypothalamic neurons and enhances leptin signaling via KATP and TRP channels to promote weight loss.\",\n      \"evidence\": \"AgRP/POMC-specific conditional KO and overexpression, LepR co-IP, and patch-clamp electrophysiology\",\n      \"pmids\": [\"36593271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which GRB10 modulates channel activity unclear\", \"Relationship to GRB10's RTK/mTORC1 functions in neurons not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GRB10's opposing positive and negative signaling roles, its degradation-adaptor function, and its mTORC1 feedback are integrated and dynamically prioritized within a single cell remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model reconciling pseudosubstrate inhibition, IRS blockade, and Nedd4-mediated degradation\", \"Full-length GRB10 structure and its conformational regulation by phosphorylation unknown\", \"Determinants of context-dependent positive versus negative output not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 20, 36, 23]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [16, 18, 41]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [20, 33, 36]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [6, 13]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [33]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 18, 37, 41]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [29, 30, 41]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [20, 33, 36]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"INSR\", \"IGF1R\", \"NEDD4\", \"AKT1\", \"RAF1\", \"FLT3\", \"GIGYF1\", \"LEPR\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}