Purified from rabbit serum by sequential epitope-specific chromatography. The antibody has been negatively preadsorbed using a non-phosphopeptide corresponding to the site of phosphorylation to remove antibody that is reactive with non-phosphorylated insulin receptor substrate 1 (IRS 1).
May mediate the control of various cellular processes by insulin. When phosphorylated by the insulin receptor binds specifically to various cellular proteins containing SH2 domains such as phosphatidylinositol 3-kinase p85 subunit or GRB2. Activates phosphatidylinositol 3-kinase when bound to the regulatory p85 subunit.
Involvement in disease
Polymorphisms in IRS1 may be involved in the etiology of non-insulin-dependent diabetes mellitus (NIDDM) [MIM:125853].
Serine phosphorylation of IRS1 is a mechanism for insulin resistance. Ser-312 phosphorylation inhibits insulin action through disruption of IRS1 interaction with the insulin receptor. Phosphorylation of Tyr-896 is required for GRB2-binding.
Western blot - Anti-IRS1 (phospho Y896) antibody (ab4873)
Peptide Competition: Extracts prepared from CHO-T cells transiently transfected with human IRS-1 and treated with 50 nM insulin for 5 minutes were resolved by SDSPAGE on a 10% Tris-glycine gel and transferred to PVDF. Membranes were blocked with a 5% BSA-TBST buffer overnight at 4oC, then were incubated with 0.50 µg/mL ab4873 antibody, following prior incubation with: no peptide (1), a generic phosphotyrosine containing peptide (2), the non-phosphopeptide corresponding to the immunogen (3), or the phosphopeptide immunogen (4). After washing, membranes were incubated with goat F(ab’)2 anti-rabbit IgG alkaline phosphatase and signals were detected using the Tropix WesternStar method. The data show that only the peptide corresponding to ab4873 blocks the antibody signal, thereby demonstrating the specificity of the antibody.
Phosphatase Stripping: Extracts prepared from CHO-T cells transiently transfected with human IRS 1 and