Abolition of G protein inhibition of alpha 1A and alpha 1B calcium channels by co-expression of the beta 3 subunit.
Three different classes of alpha 1 Ca2+ channel (alpha 1A, alpha 1B, alpha 1C) were expressed in Xenopus oocytes to determine whether G protein-mediated inhibition is an inherent property of the alpha 1 subunit itself, and if so, whether co-expression of auxiliary subunits modulates the inhibition seen. From our data it is apparent that either alpha 1A or alpha 1B Ca2+ channels expressed alone are sufficient for voltage-dependent G protein inhibition. alpha 1C Ca2+ channels expressed alone do not exhibit the G protein inhibition seen in alpha 1A and alpha 1B channels. Additionally, co-expression of the beta 3 subunit abolishes the ability of G proteins to inhibit currents through alpha 1A and alpha 1B Ca2+ channels. Differential sensitivity of alpha 1 as well as modulation of properties by beta 3 provide a potential mechanism for the regulation of G protein-mediated inhibition in neurons.
Roche
J P
JP
Department of Pharmacology, University of Massachusetts Medical School, Worcester 01655, USA.
Anantharam
V
V
Treistman
S N
SN
D000818:Animals; D015220:Calcium Channels / Q000096:biosynthesis / Q000502:physiology*; D004594:Electrophysiology; D005033:Ethylmaleimide / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008845:Microinjections; D009865:Oocytes; D018075:RNA, Complementary; D013873:Thionucleotides / Q000494:pharmacology; D014982:Xenopus laevis
D015220:Calcium Channels; D018075:RNA, Complementary; D013873:Thionucleotides; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D019204:GTP-Binding Proteins; D005033:Ethylmaleimide