Catalytic domain of the Serine/Threonine Kinase, Cyclin-Dependent protein Kinase 5
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. CDK5 is unusual in that it is regulated by non-cyclin proteins, p35 and p39. It is highly expressed in the nervous system and is critical in normal neural development and function. It plays a role in neuronal migration and differentiation, and is also important in synaptic plasticity and learning. CDK5 also participates in protecting against cell death and promoting angiogenesis. Impaired CDK5 activity is implicated in Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease and acute neuronal injury. 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 CDK5 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.