标题：Heterotrimeric G proteins in synaptoneurosome membranes are crosslinked by p-phenylenedimaleimide, yielding structures comparable in size to crosslinked tubulin and F-actin
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：1992
卷号：89
期号：13
页码：5842-5846
DOI：10.1073/pnas.89.13.5842
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have treated rat brain synaptoneurosomes with the crosslinking agent N,N'-1,4-phenylenedimaleimide under conditions that cause extensive crosslinking of tubulin, F-actin, and the alpha and beta subunits of three major types of heterotrimeric GTP-binding regulatory proteins (G(o), Gs, Gi) present in brain membranes. The major crosslinked products are coeluted from Bio-Gel sizing columns as very large structures that do not penetrate stacking gels during SDS/PAGE. The alpha subunits but not the beta subunits of Gs, G(o) and Gi also yield crosslinked products of intermediate sizes. None of the products are as small as the heterotrimeric G proteins extracted from brain by cholate or Lubrol. However, the large and intermediate crosslinked structures are strikingly similar to the large, polydisperse structures of the alpha subunits of Gs, Gi, and G(o) extracted from synaptoneurosomes by the detergent octyl glucoside, which have sedimentation properties of multimeric proteins. Several ways in which multimeric forms of G proteins can explain the dynamic and pleiotropic actions of hormones and GTP on signal-transducing systems are discussed.
