Critical role of cAMP-dependent protein kinase anchoring to the L-type calcium channel Cav1.2 via A-kinase anchor protein 150 in neurons

The cAMP-dependent protein kinase (PKA) regulates a wide array of cellular functions. In brain and heart PKA increases the activity of the L-type Ca2+ channel Ca(v)1.2 in response to beta-adrenergic stimulation. Ca(v)1.2 forms a complex with the beta(2)-adrenergic receptor, the trimeric G(S) protein, adenylyl cyclase, and PKA wherein highly localized signaling occurs [Davare, M. A., Avdonin, V., Hall, D. D., Peden, E. M., Burette, A., Weinberg, R. J., Horne, M. C., Hoshi, T., and Hell, J. W. (2001) Science 293, 98-101]. PKA primarily phosphorylates Ca(v)1.2 on serine 1928 of the central, pore-forming alpha(1)1.2 subunit. Here we demonstrate that the A-kinase anchor protein 150 (AKAP150) is critical for PKA-mediated regulation of Ca(v)1.2 in the brain. AKAP150 and MAP2B specifically co-immunoprecipitate with Ca(v)1.2 from rat brain. Recombinant AKAP75, the bovine homologue to rat AKAP150, binds directly to three different sites of alpha(1)1.2. MAP2B from rat brain also interacts with these same sites in pull-down assays. Gene disruption of AKAP150 in mice dramatically reduces co-immunoprecipitation of PKA with Ca(v)1.2 and prevents phosphorylation of serine 1928 upon beta-adrenergic stimulation in vivo. These results demonstrate the physiological relevance of PKA anchoring by AKAPs in general and AKAP150 specifically in the regulation of Ca(v)1.2 in vivo.