Beta1-Adrenergic Receptor Regulation Revisited The Role of the Extracellular N-Terminus

The actions and regulation of cardiomyocyte beta(1)ARs (beta(1) adrenergic receptors) differ in several respects from the properties described for the prototypical beta(2)AR subtype; a mechanism to explain the unique properties of the beta(1)AR subtype has never been obvious. This viewpoint summarizes recent studies that identify a novel signaling paradigm for the beta(1)AR, implicating the N terminus as a molecular determinant of beta(1)AR responsiveness.