Cyclin-dependent kinase 5 (Cdk5) and neuron-specific Cdk5 activators

摘要: While cyclin-dependent kinase 5 (Cdk5) is widely distributed in mammalian tissues and cultured cell lines, Cdk5-associated activity has been demonstrated only brains. An active form of Cdk5, called neuronal cdc2-like (Nclk) purified from brain shown to be a heterodimer Cdk5 25 kDa protein, which derived proteolytically 35 neuron-specific protein. The protein essential for the therefore designated activator, p25/35Nck5a. Nclk appears have important functions. changes Nck5a expression appear correlate with terminal differentiation neurons mouse embryonic brain. Transfection cortical dominant negative cdk5 mutants or antisense DNA may reduce neurite growth, suggesting that plays an role neuron differentiation. A number cytoskeletal proteins including neurofilament proteins, microtubule associated tau, actin binding caldesmon are vitro substrates Nclk. Although cyclin-like activity, it shows minimal amino acid sequence identity members cyclin family proteins. mechanism activation by differs Cdks full can achieved absence phosphorylation Cdk5. isoform Nck5a, 39 cloned share extensive Nck5a. These represent subfamily Cdk activators distinct cyclins.