Reconstitution of β-adrenergic regulation of Ca <sub>V</sub> 1.2: Rad-dependent and Rad-independent protein kinase A mechanisms
Moshe Katz, Suraj Subramaniam, Orna Chomsky-Hecht, Vladimir Tsemakhovich, Veit Flockerzi, Enno Klußmann, Joel A. Hirsch, Sharon W. Weiss, Nathan Dascal
Abstract
Significance The strengthening of heart contraction by epinephrine (adrenaline) and norepinephrine starts with the activation of β-adrenergic receptors and culminates in a protein kinase A–mediated increase in Ca 2+ influx through the voltage-gated Ca 2+ channel, Ca V 1.2, into cardiomyocytes. Many crucial molecular details of this vital physiological regulation remained enigmatic for decades, not the least owing to the difficulty of reconstituting the regulation in model cells. Capitalizing on the recent discovery of the central role of the Ca V 1.2-associated protein, Rad, we present a report of full reconstitution of the β-AR–Ca V 1.2 cascade in a model system, the Xenopus oocyte, and investigate crucial aspects of regulation such as the roles of auxiliary subunits and diverse forms of the channel protein.