The beta subunit controls the gating and dihydropyridine sensitivity of the skeletal muscle Ca2+ channel.
The skeletal muscle (SKM) L-type Ca2+ channel is composed of a central subunit designated alpha 1, which contains the pore and the dihydropyridine (DHP) binding domains and three associated subunits, alpha 2/delta, beta, and gamma, which influence the activity of the SKM alpha 1. Coexpression of SKM alpha 1 and SKM beta in stably transfected mouse L cells results in a dramatic increase in DHP binding accompanied by fast gated Ba2+ currents. We report here that this "SKM alpha 1 beta-related phenotype" can be converted upon intracellular trypsin treatment into a slowly inactivating, DHP sensitive "SKM alpha 1 phenotype." These observations indicate that current amplitude, fast inactivation, and DHP sensitivity are modulated by an interaction of SKM alpha 1 and SKM beta on the internal side of the membrane.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D015220:Calcium Channels / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D004095:Dihydropyridines / Q000494:pharmacology; D004563:Electrochemistry; D015640:Ion Channel Gating; D051379:Mice; D009132:Muscles / Q000378:metabolism*; D011487:Protein Conformation
D015220:Calcium Channels; D004095:Dihydropyridines; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester