Phosphatidylinositol 3-kinase regulatory subunit gamma (PI3-kinase p85-subunit gamma) (PtdIns-3-kinase p85-gamma) (p55PIK); Binds to activated (phosphorylated) protein-tyrosine kinases through its SH2 domain and regulates their kinase activity. During insulin stimulation, it also binds to IRS-1 (461 aa)