Investigating the regulation of the PCTAIRE-1 protein kinase : a new target of AMP-activated protein kinase and beyond?
PCTK1 is a Cdc2-related protein kinase that is poorly characterised. Several studies have investigated its role and regulation, and have provided some insight into its upstream regulation by PKA/CDK5 phosphorylation. Proposed physiological functions include vesicle trafficking and neurite outgrowth, however, no consensus substrate motif has been identified to date, and there are no confirmed physiological substrates. We have identified PCTK1 as a potential substrate of AMPK, a master kinase regulating energy homeostasis and a target for the widely used anti-diabetic drug metformin. Since AMPK affects many signalling pathways, understanding its downstream components will be beneficial in elucidating its mode of action and potentially identifying more specific drug targets. To analyse PCTK1 on the biochemical level, we have defined a substrate consensus motif unique for PCTK1 that is distinct from CDKs. This has enabled me to establish a PCTK1 kinase assay as an essential tool for studying its regulation. I have also validated cyclin Y as a binder and robust activator of PCTK1. I next characterised phospho-antibodies directed against key regulatory residues on PCTK1, including the activation/T-loop. This work has given a fundamental basis for PCTK1 characterisation, and provides a platform from which to continue the study of the PCTK1 kinase.
PCTAIRE-1, PCTK1, Cyclin Y, AMPK, CDK, PKA, Neurite outgrowth, Vesicle trafficking, Cell cycle, NSF, N-ethylmaleimide sensitive factor, AMP-activated protein kinase, Protein kinase A, Cyclin-dependent kinase
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