Catalytic domain of the Serine/Threonine Kinase, Cyclin-Dependent protein Kinase 1 from higher eukaryotes
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. CDK1 is also called Cell division control protein 2 (Cdc2) or p34 protein kinase, and is regulated by cyclins A, B, and E. The CDK1/cyclin A complex controls G2 phase entry and progression. CDK1/cyclin A2 has also been implicated as an important regulator of S phase events. The CDK1/cyclin B complex is critical for G2 to M phase transition. It induces mitosis by activating nuclear enzymes that regulate chromatin condensation, nuclear membrane degradation, mitosis-specific microtubule and cytoskeletal reorganization. CDK1 also associates with cyclin E and plays a role in the entry into S phase. CDK1 transcription is stable throughout the cell cycle but is modulated in some pathological conditions. It may play a role in regulating apoptosis under these conditions. In breast cancer cells, HER2 can mediate apoptosis by inactivating CDK1. Activation of CDK1 may contribute to HIV-1 induced apoptosis as well as neuronal apoptosis in neurodegenerative diseases. CDKs belong to a large family of STKs that are regulated by their cognate cyclins. Together, they are involved in the control of cell-cycle progression, transcription, and neuronal function. The CDK1 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.