Regulation of cardiac L‐type Ca2+ channel by coexpression of Gαs in Xenopus oocytes

FEBS Letters

Dascal, Nathan¹  Peres, Antonio²  Bossi, Elena²  Ivanina, Tatiana¹  Shistik, Elena¹  Blumenstein, Yakov¹ 

[1] Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel;Laboratory of Cellular and Molecular Physiology, Department of Functional and Structural Biology, University of Insubria, Via Dunant 3, 21100 Varese, Italy

关键词: Calcium channel;    G-protein;    Xenopus oocyte;   

DOI  :  10.1016/S0014-5793(99)00035-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Activation of G_αs via β-adrenergic receptors enhances the activity of cardiac voltage-dependent Ca²⁺ channels of the L-type, mainly via protein kinase A (PKA)-dependent phosphorylation. Contribution of a PKA-independent effect of G_αs has been proposed but remains controversial. We demonstrate that, in Xenopus oocytes, antisense knockdown of endogenous G_αs reduced, whereas coexpression of G_αs enhanced, currents via expressed cardiac L-type channels, independently of the presence of the auxiliary subunits α₂/δ or β_2A. Coexpression of G_αs did not increase the amount of α_1C protein in whole oocytes or in the plasma membrane (measured immunochemically). Activation of coexpressed β2 adrenergic receptors did not cause a detectable enhancement of channel activity; rather, a small cAMP-dependent decrease was observed. We conclude that coexpression of G_αs, but not its acute activation via β-adrenergic receptors, enhances the activity of the cardiac L-type Ca²⁺ channel via a PKA-independent effect on the α_1C subunit.

【 授权许可】

Unknown