Catalytic domain of the Serine/Threonine Kinase, PFTAIRE-1 kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PFTAIRE-1 is widely expressed except in the spleen and thymus. It is highly expressed in the brain, heart, pancreas, testis, and ovary, and is localized in the cytoplasm. It is regulated by cyclin D3 and is inhibited by the p21 cell cycle inhibitor. It has also been shown to interact with the membrane-associated cyclin Y, which recruits the protein to the plasma membrane. PFTAIRE-1 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 PFTAIRE-1 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.