AKT1 [AKT1/2552]

Recognizes a protein of 62kDa, which is identified as AKT1. The serine/threonine kinase Akt family contains several members, including Akt1 (also designated PKB or RacPK), Akt2 (also designated PKB tyrosine residues 740 and 751, which bind the subunit of the phosphatidylinositol 3-kinase (PI 3-kinase) complex. Activation of Akt1 by insulin or insulin-growth factor-1 (IGF-1) results in phosphorylation of both Thr 308 and Ser 473. Akt proteins become phosphorylated and activated in insulin/IGF-1-stimulated cells by an upstream kinase(s), and the activation of Akt1 and Akt2 is inhibited by the PI kinase inhibitor wortmannin.The main function of AKT is to control inhibition of apoptosis and promote cell proliferation. Survival factors can activate AKT Ser473 and Thr308 phosphorylation sites in a transcription-independent manner, resulting in the inactivation of apoptotic signaling transduction through the tumor suppressor PTEN, an antagonist to PI3-K. PTEN exerts enzymatic activity as a phosphatidylinositol-3,4,5-trisphosphate (PIP3) phosphatase, opposing PI3K activity by decreasing availability of PIP3 to proliferating cells, leading to overexpression and inappropriate activation of AKT noted in many types of cancer.