TRANSDUCIN GTPASE--GENES FOR GTP-BINDING PROTEINS

鸟嘌呤核苷酸结合蛋白(GNP)是调节 细胞新陈代谢。三个GNP，Gs，Gi和转导蛋白，由 α、β和伽马亚基介导腺苷的激素刺激 环化酶、腺苷酸环化酶的激素抑制和光激活 视网膜视杆外节的磷酸二酯酶 GNP，GO，与抑制激素受体相互作用，但不出现 来影响循环酶的活性。第五个国民生产总值，p21，是一个 参与细胞生长调控的原癌基因。要定义 这些GNPs将外界刺激偶联到 制备细胞内事件单抗和多克隆抗体， 其中一些蛋白质的cDNA克隆被分离出来。三株单抗 纯化的转导蛋白(T)制备的抗体可与TAlpha反应，但不能 在视紫红质存在下抑制TAlpha的能力 和TBetaGamma对GTP的水解性。另一种抗病毒的单抗 TAlpha与GiAlpha、GoAlpha和p21发生交叉反应。所有4种抗体 与转导蛋白的氨基末端发生反应。这些研究是 与GNPs中存在的共同表位一致。免疫接种 感染TBetaGamma的兔产生抗独特型 抗视紫红质抗体，与以下假设一致 TBetaGamma与视紫红质结合。 为了进一步明确转导蛋白的调节作用，我们克隆了一个伽马射线转导蛋白基因 亚基是从Lambdagt10基因文库中分离得到的。使用cDNA克隆 在视网膜总RNA中显示了单一大小的消息类别 Northern blotting；在大脑或 肝脏RNA。抗TGamma的多克隆抗体与Gamma无交叉反应 来自大脑或肝脏的蛋白质。因此，伽玛亚基似乎是 特定于组织。

Guanine nucleotide-binding proteins (GNP) are critical to the regulation of cellular metabolism. Three GNP's, Gs, Gi, and transducin, composed of Alpha, Beta, and Gamma subunits mediate hormonal stimulation of adenylate cyclase, hormonal inhibition of adenylate cyclase, and light activation of phosphodiesterase of retinal rod outer segments, respectively, A fourth GNP, Go, interacts with inhibitory hormone receptors, but does not appear to affect cyclase activity. A fifth GNP, p21, is a product of a proto-oncogene involved in the regulation of cell growth. To define the molecular mechanisms by which these GNPs couple external stimuli to intracellular events monoclonal and polyclonal antibodies were prepared and cDNA clones were isolated for some of these proteins. Three monoclonal antibodies prepared to purified transducin (T) reacted with TAlpha but not TBetaGamma and inhibited the ability of TAlpha in the presence of rhodopsin and TBetaGamma to hydrolyze GTP. Another monoclonal antibody against TAlpha cross-reacted with GiAlpha, GoAlpha and p21. All 4 antibodies reacted with the amino-terminal region of transducin. These studies are consistent with the presence of common epitopes in GNPs. Immunization of rabbits with TBetaGamma resulted in the production of anti-idiotypic antibodies against rhodopsin, consistent with the hypothesis that TBetaGamma binds to rhodopsin. To define further the regulation of transducin, a cDNA clone for the Gamma subunit was isolated from a Lambdagt10 cDNA library. Using the cDNA clone a single size class of message was demonstrated in total retinal RNA by Northern blotting; no homologous messages were detected in either brain or liver RNA. Polyclonal antibodies to TGamma did not cross-react with Gamma proteins from brain or liver. Thus, Gamma subunits appear to be tissue-specific.