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- 题目:
- Interaction between the RGS domain of RGS4 with G protein alpha subunits mediates the voltage-dependent relaxation of the G protein-gated potassium channel.
- 作者:
- Inanobe(A),Fujita(S),Makino(Y),Matsushita(K),Ishii(M),Chachin(M),Kurachi(Y)
- 状态:
- 发布时间2001-08-16 , 更新时间 2014-06-13
- 期刊:
- J Physiol
- 摘要:
- 1. In native cardiac myocytes, there is a time dependence to the G protein-gated inwardly rectifying K(+) (K(G)) channel current during voltage steps that accelerates as the concentration of acetylcholine is increased. This phenomenon has been called 'relaxation' and is not reproduced in the reconstituted Kir3.1/Kir3.4 channel in Xenopus oocytes. We have shown that RGS4, a regulator of G protein signalling, restores relaxation to the reconstituted Kir3.1/Kir3.4 channel. In this study, we examined the mechanism of this phenomenon by expressing various combinations of membrane receptors, G proteins, Kir3.0 subunits and mutants of RGS4 in Xenopus oocytes. 2. RGS4 restored relaxation to K(G) channels activated by the pertussis toxin (PTX)-sensitive G protein-coupled m(2)-muscarinic receptor but not to those activated by the G(s) protein-coupled beta(2)-adrenergic receptor. 3. RGS4 induced relaxation not only in heteromeric K(G) channels composed of Kir3.1 and Kir3.4 but also in homomeric assemblies of either an active mutant of Kir3.1 (Kir3.1/F137S) or an isoform of Kir3.2 (Kir3.2d). 4. Truncation mutants of RGS4 showed that the RGS domain itself was essential to reproduce the effect of wild-type RGS4 on the K(G) channel. 5. The mutation of residues in the RGS domain which interact with the alpha subunit of the G protein (G(alpha)) impaired the effect of RGS4. 6. This study therefore shows that interaction between the RGS domain and PTX-sensitive G(alpha) subunits mediates the effect of RGS4 on the agonist concentration-dependent relaxation of K(G) channels.
- 语言:
- eng
- DOI:
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