Cyclin-dependent Kinase 5 (Cdk5) Activation Domain of Neuronal Cdk5 Activator EVIDENCE OF THE EXISTENCE OF CYCLIN FOLD IN NEURONAL Cdk5a ACTIVATOR*

Neuronal Cdk5 activator (Nck5a) differs from other cyclin-dependent kinase (Cdk) activators in that its amino acid sequence is only marginally similar to the cyclin consensus sequence. Nevertheless, computer modeling has suggested that Nck5a contains the cyclin-fold motif recently identified in the crystal structure of cyclin A. In the present study, a number of truncation mutants and substitution mutants of the Nck5a were produced and tested …