Catalytic domain of Yeast Protein Kinase 1-like Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This subfamily is composed of fungal proteins with similarity to the AGC STKs, Saccharomyces cerevisiae YPK1 and Schizosaccharomyces pombe Gad8p. YPK1 is required for cell growth and acts as a downstream kinase in the sphingolipid-mediated signaling pathway of yeast. It also plays a role in efficient endocytosis and in the maintenance of cell wall integrity. Gad8p is a downstream target of Tor1p, the fission yeast homolog of mTOR. It plays a role in cell growth and sexual development. The YPK1-like 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.