Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Ca2+ current enhancement by alpha 2/delta and beta subunits in Xenopus oocytes: contribution of changes in channel gating and alpha 1 protein level.
Shistik E
,
Ivanina T
,
Puri T
,
Hosey M
,
Dascal N
.
???displayArticle.abstract???
1. A combined biochemical and electrophysiological approach was used to determine the mechanism by which the auxiliary subunits of Ca2+ channel enhance the macroscopic Ca2+ currents. Xenopus oocytes were injected with RNA of the main pore-forming subunit (cardiac: alpha 1C), and various combinations of RNAs of the auxiliary subunits (alpha 2/delta and beta 2A). 2. The single channel open probability (Po; measured at 0 mV) was increased approximately 3-, approximately 8- and approximately 35-fold by alpha 2/delta, beta 2A and alpha 2/delta+beta 2A, respectively. The whole-cell Ca2+ channel current was increased approximately 8- to 10-fold by either alpha 2/delta or beta 2A, and synergistically > 100-fold by alpha 2/delta+beta 2A. The amount of 35S-labelled alpha 1 protein in the plasma membrane was not changed by coexpression of beta 2A, but was tripled by coexpression of alpha 2/delta (either with or without beta). 3. We conclude that the increase in macroscopic current by alpha 2/delta is equally due to changes in amount of alpha 1 in the plasma membrane and an increase in Po, whereas all of the effect of beta 2A is due to an increase in Po. The synergy between alpha 2/delta and beta in increasing the macroscopic current is due mainly to synergistic changes in channel gating.
Chang,
Dihydropyridine and phenylalkylamine receptors associated with cardiac and skeletal muscle calcium channels are structurally different.
1988, Pubmed
Chang,
Dihydropyridine and phenylalkylamine receptors associated with cardiac and skeletal muscle calcium channels are structurally different.
1988,
Pubmed
De Jongh,
Characterization of the two size forms of the alpha 1 subunit of skeletal muscle L-type calcium channels.
1991,
Pubmed
Hess,
Different modes of Ca channel gating behaviour favoured by dihydropyridine Ca agonists and antagonists.
,
Pubmed
Hofmann,
Molecular basis for Ca2+ channel diversity.
1994,
Pubmed
Hullin,
Calcium channel beta subunit heterogeneity: functional expression of cloned cDNA from heart, aorta and brain.
1992,
Pubmed
,
Xenbase
Isom,
Auxiliary subunits of voltage-gated ion channels.
1994,
Pubmed
Ivanina,
Phosphorylation by protein kinase A of RCK1 K+ channels expressed in Xenopus oocytes.
1994,
Pubmed
,
Xenbase
Lacerda,
Normalization of current kinetics by interaction between the alpha 1 and beta subunits of the skeletal muscle dihydropyridine-sensitive Ca2+ channel.
1991,
Pubmed
Mikami,
Primary structure and functional expression of the cardiac dihydropyridine-sensitive calcium channel.
1989,
Pubmed
,
Xenbase
Mori,
Primary structure and functional expression from complementary DNA of a brain calcium channel.
1991,
Pubmed
,
Xenbase
Neely,
Dual activation of the cardiac Ca2+ channel alpha 1C-subunit and its modulation by the beta-subunit.
1995,
Pubmed
,
Xenbase
Neely,
Potentiation by the beta subunit of the ratio of the ionic current to the charge movement in the cardiac calcium channel.
1993,
Pubmed
,
Xenbase
Nishimura,
Requirement of the calcium channel beta subunit for functional conformation.
1993,
Pubmed
Singer,
The roles of the subunits in the function of the calcium channel.
1991,
Pubmed
,
Xenbase
Varadi,
Acceleration of activation and inactivation by the beta subunit of the skeletal muscle calcium channel.
1991,
Pubmed
Wakamori,
Single-channel analysis of a cloned human heart L-type Ca2+ channel alpha 1 subunit and the effects of a cardiac beta subunit.
1993,
Pubmed
,
Xenbase
Yoshida,
Cyclic AMP-dependent phosphorylation and regulation of the cardiac dihydropyridine-sensitive Ca channel.
1992,
Pubmed
