- Beta-adrenergic regulation requires direct anchoring of PKA to cardiac CaV1.2 channels via a leucine zipper interaction with A kinase-anchoring protein 15. Hulme, J.T., Lin, T.W., Westenbroek, R.E., Scheuer, T., Catterall, W.A. Proc. Natl. Acad. Sci. U.S.A. (2003)