Catalytic domain of the Serine/Threonine Kinase, Protein Kinase B gamma (also called Akt3)
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKB-gamma is predominantly expressed in neuronal tissues. Mice deficient in PKB-gamma show a reduction in brain weight due to the decreases in cell size and cell number. PKB-gamma has also been shown to be upregulated in estrogen-deficient breast cancer cells, androgen-independent prostate cancer cells, and primary ovarian tumors. It acts as a key mediator in the genesis of ovarian cancer. PKB contains an N-terminal pleckstrin homology (PH) domain and a C-terminal catalytic domain. The PKB-gamma 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.