Catalytic domain of the Serine/Threonine Kinase, PCTAIRE-3 kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PCTAIRE-3 shows a restricted pattern of expression and is present in brain, kidney, and intestine. It is elevated in Alzheimer's disease (AD) and has been shown to associate with paired helical filaments (PHFs) and stimulate Tau phosphorylation. As AD progresses, phosphorylated Tau aggregates and forms PHFs, which leads to the formation of neurofibrillary tangles. In human glioma cells, PCTAIRE-3 induces cell cycle arrest and cell death. PCTAIRE-3 shares sequence similarity with Cyclin-Dependent Kinases (CDKs), which belong to a large family of STKs that are regulated by their cognate cyclins. Together, CDKs and cyclins are involved in the control of cell-cycle progression, transcription, and neuronal function. The PCTAIRE-3 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.