GENES FOR GTP-BINDING PROTEINS

GTP 结合蛋白的基因

• 批准号: 3919999
• 负责人: S R PRICE
• 金额: --
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3919999
• 关键词: ADP ribosylation; G protein; adenylate cyclase; catalyst; cholera toxin; complementary DNA; enzyme induction /repression; enzyme mechanism; enzyme structure; enzyme substrate; genetic library; guanine nucleotides; guanosine triphosphate; human tissue; molecular cloning; muscarinic receptor; nucleic acid probes; nucleic acid sequence; protein sequence; rhodopsin

Choleragen (cholera toxin) catalyzes the ADP-ribosylation of Gs alpha, the stimulatory guanine nucleotide-binding protein (GNP) of the adenylyl cyclase system which couples hormone or neurotransmitter receptors to the cyclase catalytic unit. ADP- ribosylation of Gs alpha increases sensitivity to activation by GTP by inhibiting its intrinsic GTPase, thereby ultimately activating adenylyl cyclase and raising intracellular cyclic AMP. Recently, one membrane and two soluble guanine nucleotide-binding proteins that enhance the choleragen-catalyzed ADP-ribosylation of Gs alpha have been purified from bovine brain. These ADP. ribosylation factors (ARFs) also serve as toxin substrates. To define the structure and function of the ARFs, we isolated a cDNA clone from a bovine retinal library using a mixed oligonucleotide probe whose sequence was based on the partial amino acid sequence of a bovine brain soluble ARF. There were only two differences between the deduced amino acid sequence of clone lambda ARF2B and sequences of two CNBr peptides of the ARF protein (60 amino acids total). Comparison of the deduced amino acid sequences of ARF, Go alpha (GNP isolated from bovine brain and thought to regulate ion channels), and c-Ha-ras p21 protein revealed similarities in regions putatively involved in guanine nucleotide binding and GTP hydrolysis. ARF lacks a sequence analogous to the site of choleragen modification in the c subunits of the GNPs. We conclude that ARF is a GNP that interacts with the Al subunit of choleragen in a manner quite different from other GNPs. This interaction modifies the catalytic properties of the toxin, in addition to allowing the ARF protein to act as a substrate for ADP- ribosylation.

霍乱原（霍乱毒素）催化 Gs α，刺激性鸟嘌呤核苷酸结合蛋白（GNP） 腺苷酸环化酶系统，该系统与激素或 环化酶催化单位的神经递质受体。 ADP- Gs α的核糖基化增加对GTP激活的敏感性 通过抑制其内在的GT3，从而最终激活 腺苷酸环化酶和提高细胞内环AMP。 最近，一个膜和两个可溶性鸟嘌呤核苷酸结合 增强促胆固醇原催化的ADP-核糖基化的蛋白质 从牛脑中提纯了Gs α。 这些ADP。 核糖基化因子（ARF）也用作毒素底物。 到 为了进一步明确ARF的结构和功能，我们分离了一个cDNA， 使用混合寡核苷酸从牛视网膜文库克隆 其序列基于部分氨基酸序列的探针 牛脑可溶性急性肾衰 只有两点不同 克隆λ ARF 2B的推导氨基酸序列与 ARF蛋白的两个CNBr肽的序列（60个氨基酸 共计）。 ARF、Go蛋白氨基酸序列的比较 α（从牛脑中分离的GNP，被认为是调节离子的 和c-Ha-ras p21蛋白揭示了相似性， 参与鸟嘌呤核苷酸结合和GTP的嘌呤区 水解 ARF缺乏类似于 GNP的c亚基中的胆固醇原修饰。 我们的结论 ARF是一种GNP，与霍乱原的A1亚基相互作用， 与其他GNP完全不同。 这种相互作用 改变了毒素的催化特性， 允许ARF蛋白充当ADP的底物- 核糖基化