Catalytic domain of the Serine/Threonine Kinase, Protein Kinase B beta (also called Akt2)
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKB-beta is the predominant PKB isoform expressed in insulin-responsive tissues. It plays a critical role in the regulation of glucose homeostasis. It is also implicated in muscle cell differentiation. Mice deficient in PKB-beta display normal growth weights but exhibit severe insulin resistance and diabetes, accompanied by lipoatrophy and B-cell failure. PKB contains an N-terminal pleckstrin homology (PH) domain and a C-terminal catalytic domain.The PKB-beta subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.