期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1993
卷号：90
期号：14
页码：6596-6600
DOI：10.1073/pnas.90.14.6596
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Injection of rat atrial RNA into Xenopus oocytes resulted in the expression of 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 microM Ba2+. I5HT was suppressed by intracellular injection of the nonhydrolyzable analog of GDP, guanosine 5'-[beta-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 alpha subunit of a PTX-sensitive G protein, G(i2), 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.
