IndraLab

"The specific activity of four candidate protein-tyrosine phosphatases (protein-tyrosine phosphatase 1b (ptp1b), sh2 domain-containing ptpase-2 (shp-2), leukocyte common antigen-related (lar), and leukocyte antigen-related phosphatase) (lrp) toward irs-1 dephosphorylation was studied using recombinant proteins in vitro. Ptp1b exhibited the highest specific activity these results provide new insight into novel molecular interactions involving ptp1b and grb2 that may influence the steady-state capacity of irs-1 to function as a phosphotyrosine scaffold and possibly affect the balance of postreceptor insulin signaling."

"Therefore, during insulin stimulation irs-1 undergoes tyrosine phosphorylation, and a portion of tyrosine phosphorylated irs-1 associated with the insulin receptor. The insulin receptor substrate-1 (irs-1) is rapidly phosphorylated on several tyrosine residues by the activated insulin receptor. Insulin signals are mediated through tyrosine phosphorylation of specific proteins such as insulin receptor substrate 1 (irs-1) and shc by the activated insulin receptor (ir)."

"The specific activity of four candidate protein-tyrosine phosphatases (protein-tyrosine phosphatase 1b (ptp1b), sh2 domain-containing ptpase-2 (shp-2), leukocyte common antigen-related (lar), and leukocyte antigen-related phosphatase) (lrp) toward irs-1 dephosphorylation was studied using recombinant proteins in vitro. Ptp1b exhibited the highest specific activity these results provide new insight into novel molecular interactions involving ptp1b and grb2 that may influence the steady-state capacity of irs-1 to function as a phosphotyrosine scaffold and possibly affect the balance of postreceptor insulin signaling."

"Furthermore, IGF-1 stimulates tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and IRS-2 and their association with the p85 subunit of phosphoinositide-3 kinase (PI3K)."

"Here we show that stimulation by insulin of freshly isolated primary adipocytes resulted in the expected rapid tyrosine phosphorylation of the insulin receptor, IRS-1 and IRS-3. Inhibition of PI 3-kinase enhanced the insulin-stimulated phosphorylation of IRS-1 on (i) Tyr(612) and Tyr(941) (p85 binding sites), concomitant with an increased association of the p85 subunit of PI 3-kinase; (ii) Tyr(896) (a Grb2 binding site); and (iii) Tyr(1229) (an SHP-2 binding site), although little or no binding of SHP-2 to IRS-1 was detectable under any conditions."