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：1999
卷号：96
期号：5
页码：2503-2507
DOI：10.1073/pnas.96.5.2503
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The G protein {beta} subunit G{beta}5 deviates significantly from the other four members of G{beta}-subunit family in amino acid sequence and subcellular localization. To detect the protein targets of G{beta}5 in vivo, we have isolated a native G{beta}5 protein complex from the retinal cytosolic fraction and identified the protein tightly associated with G{beta}5 as the regulator of G protein signaling (RGS) protein, RGS7. Here we show that complexes of G{beta}5 with RGS proteins can be formed in vitro from the recombinant proteins. The reconstituted G{beta}5-RGS dimers are similar to the native retinal complex in their behavior on gel-filtration and cation-exchange chromatographies and can be immunoprecipitated with either anti-G{beta}5 or anti-RGS7 antibodies. The specific G{beta}5-RGS7 interaction is determined by a distinct domain in RGS that has a striking homology to G{gamma} subunits. Deletion of this domain prevents the RGS7-G{beta}5 binding, although the interaction with G is retained. Substitution of the G{gamma}-like domain of RGS7 with a portion of G{gamma}1 changes its binding specificity from G{beta}5 to G{beta}1. The interaction of G{beta}5 with RGS7 blocked the binding of RGS7 to the G subunit Go, indicating that G{beta}5 is a specific RGS inhibitor.
