Catalytic domain of PRKX-like Protein Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. Members of this group include human PRKX (X chromosome-encoded protein kinase), Drosophila DC2, and similar proteins. PRKX is present in many tissues including fetal and adult brain, kidney, and lung. The PRKX gene is located in the Xp22.3 subregion and has a homolog called PRKY on the Y chromosome. An abnormal interchange between PRKX aand PRKY leads to the sex reversal disorder of XX males and XY females. PRKX is implicated in granulocyte/macrophage lineage differentiation, renal cell epithelial migration, and tubular morphogenesis in the developing kidney. The PRKX-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.