Insulin receptor substrate
This sequence, KKHTDDGYMPMSPGVA, is from insulin receptor substrate-1 (IRS-1) inclusive of Tyr608 (mouse) -Tyr612 (human). It contains the insulin receptor tyrosine kinase substrate motif YMXM (Tyr-Met-X-Met). This peptide has been used as a substrate for purified insulin receptor (Km=90 µM) and other tyrosine kinases in phosphocellulose binding assays. The tyrosine phosphorylated version of this peptide binds to phosphatidylinositol 3-kinase (PI 3-kinase) SH2 domain and activates the enzyme.