Cyclin-dependent kinase 5 phosphorylates signal transducer and activator of transcription 3 and regulates its transcriptional activity.

The activity of cyclin-dependent kinase 5 (Cdk5) depends on the association with one of its activators, p35 and p39, which are prominently expressed in the nervous system. Studies on the repertoire of protein substrates for Cdk5 have implicated the involvement of Cdk5 in neuronal migration and synaptic plasticity. Our recent analysis of the sequence of signal transducer and activator of transcription (STAT)3, a key transcription factor, reveals the presence of potential Cdk5 phosphorylation site.