G protein multiplicity in eukaryotic signal transduction systems.
G protein multiplicity in eukaryotic signal transduction systems.
复制标题
真核信号转导系统中的 G 蛋白多样性。
DOI：
10.1021/bi00414a001
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Simon,MI
中科院分区：
文献类型：
--
作者：
Lochrie,MA;Simon,MI
1988年3月2日收到的修订版Mandarin pt（jr蛋白包括鸟嘌呤核苷酸结合调节蛋白的特定家族，其在真核细胞中的多种跨膜信号传导过程中充当中间体（Gilman，1987）。它们位于细胞膜的细胞质表面，在那里它们将配体结合的受体物理偶联到产生细胞内代谢变化的效应蛋白的调节上。G蛋白是由α（MT 39000-54000）、γ（MT 35000或36000）和γ（Mr 8000-10000）亚基组成的异源三聚体。a亚基与鸟嘌呤核苷酸相互作用。β和y亚基形成紧密结合的β y复合物。不同的G蛋白含有不同的α亚基和可能不同的γ亚基，但只有一种或两种α亚基。在这个过程中，配体结合受体诱导α亚基上的核苷酸交换反应，其中GDP可以交换为GTP。在最具特征的G蛋白偶联系统中，GTP直接调节效应蛋白。1、;- GTP的调节活性由α亚基的内在GTP酶活性终止，并且产生的-GDP然后可以启动另一个GTP结合和水解循环。通过多次循环事件，可以获得原始刺激的大放大。两种细菌毒素可以通过α亚基的共价ADP-核糖基化在特定阶段中断信号转导循环。百日咳毒素使受体与G蛋白解偶联以消除信号传导，而霍乱毒素抑制G蛋白活性以增强信号传导。
Revised Manuscript Received March 2, 1988 (jrproteins comprise a specific family of guanine nucleotide binding regulatory proteins that serve as intermediaries in a variety of transmembrane signaling processes in eukaryotic cells (Gilman, 1987). They are located on the cytoplasmic surface of membranes, where they physically couple ligand-bound receptors to the regulation of effectorproteins which produce changes in intracellular metabolism. G proteins are heterotrimers composed of a (MT 39000-54000), ß (MT 35000 or 36000), and y (Mr 8000-10000) subunits. The a subunit interacts with guanine nucleotides. The ß and y subunits form a tightly associated ßy complex. Different G proteins contain different a and probablydifferent y subunits but only one or two types of ß subunits.G proteins function by utilizing a guanine nucleotide binding and hydrolysis cycle. In this process ligand-bound receptors induce a nucleotide exchange reaction on the a subunit in which GDP can be exchanged for GTP. In the best characterized G protein coupled systems-GTP directly regulates effector proteins. 1 The; regulatory activity of-GTP is ter-minated by an intrinsic GTPase activity of the a subunit, and the-GDP that results can then initiate another GTP binding and hydrolysis cycle. Throughmultiple cycling events, a large amplification of the original stimulus can be obtained. Two bacterial toxins can interrupt the signal transduction cycle at specific stages through covalent ADP-ribosylation of the a subunit. Pertussis toxin uncouples receptors from G proteins to abolish signaling, while cholera toxin inhibits GTPase ac-tivity to enhance signalling.