Cloning of the beta(2a) subunit of the voltage-dependent calcium channel from human heart: cooperative effect of alpha(2)/delta and beta(2a) on the membrane expression of the alpha(1C) subunit.
Expression and membrane localization of an epitope-tagged human Ca(2+) channel alpha(1C) subunit were monitored in Xenopus oocytes by confocal microscopy and electrophysiological recording. When alpha(2)/delta and beta(2a) were separately coexpressed with the alpha(1C) subunit, assessment by confocal microscopy showed an 86 and 225% increase of the channel density, respectively. Simultaneous coexpression of alpha(2)/delta and beta(2a) subunits resulted in a cooperative (470%) increase. Electrophysiological measurements performed in parallel revealed that the current augmentation by the alpha(2)/delta subunit is totally attributable to an increase in channel density, whereas the beta(2a) subunit, in addition to increasing channel density, also facilitates channel opening.
Yamaguchi
H
H
Institute of Molecular Pharmacology, Department of Cell Biology, University of Cincinnati, College of Medicine, 231 Bethesda Avenue, Cincinnati, Ohio, 45267-0828, USA.
Okuda
M
M
Mikala
G
G
Fukasawa
K
K
Varadi
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001464:Barium / Q000494:pharmacology; D015220:Calcium Channels / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D019976:Cloning, Organism; D006321:Heart / Q000502:physiology; D006801:Humans; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009865:Oocytes / Q000502:physiology; D020836:Protein Structure, Quaternary; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014981:Xenopus; D014982:Xenopus laevis
D015220:Calcium Channels; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D001464:Barium