The Cdk5-p35 kinase associates with the Golgi apparatus and regulates membrane traffic

We show here that an active Cdk5-p35 kinase is present in Golgi membranes, where it associates with a detergent-insoluble fraction containing actin. In addition, Cdk5-p35-dependent phosphorylation of alpha-PAK immunoreactive protein species was detected in Golgi membranes, as well as an interaction with the small GTPase, Cdc42. Moreover, antisense oligonucleotide suppression of Cdk5 or p35 in young cultured neurons, as well as inhibition of Cdk5 activity with olomoucine, blocks the formation of membrane vesicles from the Golgi apparatus. Taken together, these results show a novel subcellular localization of this kinase and suggest a role for Cdk5-p35 in membrane traffic during neuronal process outgrowth.