Editorial
Jyotshnabala Kanungo
Abstract
Cyclin-dependent kinase 5 (Cdk5) was identified almost two decades ago as a Tau kinase specific to the nervous system. Shortly after its discovery, it was revealed that this atypical member of the CDK family does not partner with cyclins but with two other proteins, p35 and p39. P35 is predominantly expressed in post-mitotic neurons, whereas p39 is expressed in many different tissues including the brain, pancreas, muscle cells, neutrophils, and many other cell types. A proline-directed serine/threonine (S/T) kinase, predominantly active in the nervous system, Cdk5 regulates a multitude of functions including nervous system development, neuronal migration, cytoskeletal dynamics, axonal guidance, synaptic plasticity, neurotransmission, neuronal survival and death, to mention a few. In association with its ubiquitous expression in other tissues, Cdk5 is implicated in a wide range of functions, such as gene transcription, vesicular transport, apoptosis, cell adhesion, migration, exocytosis, etc.