You are currently viewing the abstract.
View Full TextLog in to view the full text
AAAS login provides access to Science for AAAS members, and access to other journals in the Science family to users who have purchased individual subscriptions.
Register for free to read this article
As a service to the community, this article is available for free. Existing users log in.
More options
Download and print this article for your personal scholarly, research, and educational use.
Buy a single issue of Science for just $15 USD.
Abstract
During the fight-or-flight response, the sympathetic nervous system stimulates L-type calcium ion (Ca2+) currents conducted by CaV1 channels through activation of β-adrenergic receptors, adenylyl cyclase, and phosphorylation by adenosine 3′,5′-monophosphate–dependent protein kinase [also known as protein kinase A (PKA)], increasing contractility of skeletal and cardiac muscles. We reconstituted this regulation of cardiac CaV1.2 channels in non-muscle cells by forming an autoinhibitory signaling complex composed of CaV1.2Δ1800 (a form of the channel truncated at the in vivo site of proteolytic processing), its noncovalently associated distal carboxyl-terminal domain, the auxiliary α2δ1 and β2b subunits, and A-kinase anchoring protein 15 (AKAP15). A factor of 3.6 range of CaV1.2 channel activity was observed from a minimum in the presence of protein kinase inhibitors to a maximum upon activation of adenylyl cyclase. Basal CaV1.2 channel activity in unstimulated cells was regulated by phosphorylation of serine-1700 and threonine-1704, two residues located at the interface between the distal and the proximal carboxyl-terminal regulatory domains, whereas further stimulation of channel activity through the PKA signaling pathway only required phosphorylation of serine-1700. Our results define a conceptual framework for CaV1.2 channel regulation and identify sites of phosphorylation that regulate channel activity.