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Expression of an atrial G-protein-activated potassium channel in Xenopus oocytes

Dascal, Nathan and Lim, Nancy F. and Schreibmayer, Wolfgang and Wang, Weizhen and Davidson, Norman and Lester, Henry A. (1993) Expression of an atrial G-protein-activated potassium channel in Xenopus oocytes. Proceedings of the National Academy of Sciences of the United States of America, 90 (14). pp. 6596-6600. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:DASpnas93

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Abstract

Injection of rat atrial RNA into Xenopus oocytes resulted in the expression of a guanine nucleotide binding (G) protein-activated K+ channel. Current through the channel could be activated by acetylcholine or, if RNA encoding a neuronal 5HT1A receptor was coinjected with atrial RNA, by serotonin (5HT). A 5HT-evoked current (I5HT) was observed in oocytes injected with ventricle RNA fractions (of 2.5-5.5 kb) and 5HT1A receptor RNA. I5HT displayed strong inward rectification with very little conductance above the K+ equilibrium potential, was highly selective for K+ over Na+, and was blocked by 5-300 µM Ba2+. I5HT was suppressed by intracellular injection of the nonhydrolyzable analog of GDP, guanosine 5'-[ß-thio]diphosphate, but not by treatment with pertussis toxin (PTX), suggesting coupling of the receptor to the G-protein-activated K+ channel via a PTX-insensitive G protein, possibly endogenously present in the oocyte. Coexpression of the subunit of a PTX-sensitive G protein, Gi2, rendered I5HT sensitive to PTX inhibition. Native oocytes displayed a constitutively active inwardly rectifying K+ current with a lower sensitivity to Ba2+ block; expression of a similar current was also directed by atrial or ventricle RNA of 1.5-3 kb. Xenopus oocytes may be employed for cloning of the G-protein-activated K+ channel cDNA and for studying the coupling between this channel and G proteins.


Item Type:Article
Additional Information:© 1993 by the National Academy of Sciences. Contributed by Norman Davidson, April 9, 1993. We thank P. Hartig and M.I. Simon for providing the cDNAs of SHT1A-R and Gi2α. This work was supported by U.S. Public Health Service Grants GM-29836 and MH-49176, by U.S.-Israel Binational Science Foundation, a National Research Service Award, and Austrian Research Foundation. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Subject Keywords:MUSCARINIC K+ CHANNELS; GTP-BINDING PROTEINS; BETA-GAMMA-SUBUNITS; MESSENGER-RNA; ACETYLCHOLINE ACTIVATION; ALPHA-SUBUNITS; ION CHANNELS; RECEPTORS; CELLS; SEROTONIN
Record Number:CaltechAUTHORS:DASpnas93
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:DASpnas93
Alternative URL:http://dx.doi.org/10.1073/pnas.90.14.6596
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10662
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Jun 2008
Last Modified:14 Nov 2014 19:20

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