Cloning and expression of a cardiac/brain beta subunit of the L-type calcium channel.
The skeletal muscle dihydropyridine receptor/Ca2+ channel is composed of five protein components (alpha 1, alpha 2 delta, beta, and gamma). Only two such components, alpha 1 and alpha 2, have been identified in heart. The present study reports the cloning and expression of a novel beta gene that is expressed in heart, lung, and brain. Coexpression of this beta with a cardiac alpha 1 in Xenopus oocytes causes the following changes in Ca2+ channel activity: it increases peak currents, accelerates activation kinetics, and shifts the current-voltage relationship toward more hyperpolarized potentials. It also increases dihydropyridine binding to alpha 1 in COS cells. These results indicate that the cardiac L-type Ca2+ channel has a similar subunit structure as in skeletal muscle, and provides evidence for the modulatory role of the beta subunit.
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
E
E
Perez-Reyes
A
A
Castellano
H S
HS
Kim
P
P
Bertrand
E
E
Baggstrom
A E
AE
Lacerda
X Y
XY
Wei
L
L
Birnbaumer
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology*; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods; D015723:Gene Library; D006321:Heart / Q000502:physiology*; D007700:Kinetics; D046911:Macromolecular Substances; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D009132:Muscles / Q000502:physiology; D009838:Oligodeoxyribonucleotides; D009865:Oocytes / Q000502:physiology; D016133:Polymerase Chain Reaction; D051381:Rats; D011978:Receptors, Nicotinic / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection; D014981:Xenopus
D015220:Calcium Channels; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D011978:Receptors, Nicotinic; D011994:Recombinant Proteins; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester