Birnbaumer L, Abramowitz J, Brown A M
Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
Biochim Biophys Acta. 1990 May 7;1031(2):163-224. doi: 10.1016/0304-4157(90)90007-y.
The primary structure of G proteins as deduced from purified proteins and cloned subunits is presented. When known, their functions are discussed, as are recent data on direct regulation of ionic channels by G proteins. Experiments on expression of alpha subunits, either in bacteria or by in vitro translation of mRNA synthesized from cDNA are presented as tools for definitive assignment of function to a given G protein. The dynamics of G protein-mediated signal transduction are discussed. Key points include the existence of two superimposed regulatory cycles in which upon activation by GTP, G proteins dissociate into alpha and beta gamma and their dissociated alpha subunits hydrolyze GTP. The action of receptors to catalyze rather than regulate by allostery the activation of G proteins by GTP is emphasized, as is the role of subunit dissociation, without which receptors could not act as catalysts. To facilitate the reading of this review, we have presented the various subtopics of this rapidly expanding field in sections 1-1X, each of which is organized as a self-contained sub-chapter that can be read independently of the others.
本文介绍了从纯化蛋白和克隆亚基推导得出的G蛋白一级结构。在已知的情况下，将讨论它们的功能，以及G蛋白对离子通道直接调节的最新数据。介绍了在细菌中表达α亚基，或通过体外翻译从cDNA合成的mRNA来表达α亚基的实验，这些实验可作为明确给定G蛋白功能的工具。文中还讨论了G蛋白介导的信号转导动力学。要点包括存在两个叠加的调节循环，在这些循环中，G蛋白被GTP激活后会解离为α和βγ亚基，且解离后的α亚基会水解GTP。强调了受体催化G蛋白被GTP激活而非通过变构调节的作用，以及亚基解离的作用，没有亚基解离，受体就无法起到催化作用。为便于阅读本综述，我们在第1至9节中介绍了这个快速发展领域的各个子主题，每一节都组织成一个独立的子章节，可以独立于其他章节阅读。
