Pericentrin anchors protein kinase A at the centrosome through a newly identified RII-binding domain

Centrosomes orchestrate microtubule nucleation and spindle assembly during cell division 1,2] and have long been recognized as major anchoring sites for cAMP-dependent protein kinase (PKA) 3,4]. Subcellular compartmentalization of PKA is achieved through the association of the PKA holoenzyme with A-kinase anchoring proteins (AKAPs) 5,6]. AKAPs have been shown to contain a conserved helical motif, responsible for binding to the type II regulatory subunit (RII) of PKA, and a specific targeting motif unique to each anchoring protein that directs the kinase to specific intracellular locations. Here, we show that pericentrin, an integral component of the pericentriolar matrix of the centrosome that has been shown to regulate centrosome assembly and organization, directly interacts with PKA through a newly identified binding domain. We demonstrate that both RII and the catalytic subunit of PKA coimmunoprecipitate with pericentrin isolated from HEK-293 cell extracts and that PKA catalytic activity is enriched in pericentrin immunoprecipitates. The interaction of pericentrin with RII is mediated through a binding domain of 100 amino acids which does not exhibit the structural characteristics of similar regions on conventional AKAPs. Collectively, these results provide strong evidence that pericentrin is an AKAP in vivo.