Referenced in: none

Automatically associated channels: Kv7.1 , Slo1

Title: Overexpression of beta2-adrenergic receptors cAMP-dependent protein kinase phosphorylates and modulates slow delayed rectifier potassium channels expressed in murine heart: evidence for receptor/channel co-localization.

Authors: Keith W Dilly, Junko Kurokawa, Cecile Terrenoire, Steven Reiken, W J Lederer, Andrew R Marks, Robert S Kass

Journal, date & volume: J. Biol. Chem., 2004 Sep 24 , 279, 40778-87

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/15272004

Abstract
The cardiac slow delayed rectifier potassium channel (IKs), comprised of (KCNQ1) and beta (KCNE1) subunits, is regulated by sympathetic nervous stimulation, with activation of beta-adrenergic receptors PKA phosphorylating IKs channels. We examined the effects of 2-adrenergic receptors (beta2-AR) on IKs in cardiac ventricular myocytes from transgenic mice expressing fusion proteins of IKs subunits and hbeta2-ARs. KCNQ1 and beta2-ARs were localized to the same subcellular regions, sharing intimate localization within nanometers of each other. In IKs/B2-AR myocytes, IKs density was increased, and activation shifted in the hyperpolarizing direction; IKs was not further modulated by exposure to isoproterenol, and KCNQ1 was found to be PKA-phosphorylated. Conversely, beta2-AR overexpression did not affect L-type calcium channel current (ICaL) under basal conditions with ICaL remaining responsive to cAMP. These data indicate intimate association of KCNQ1 and beta2-ARs and that beta2-AR signaling can modulate the function of IKs channels under conditions of increased beta2-AR expression, even in the absence of exogenous beta-AR agonist.