CHARACTERIZATION OF A NOVEL G PROTEIN IN HUMAN PLATELETS

人类血小板中新型 G 蛋白的表征

• 批准号: 3364139
• 负责人: LAWRENCE F BRASS
• 金额: $ 24.4万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-07-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3364139
• 关键词: G protein; antibody; calcium channel; cell membrane; electrofocusing; electron microscopy; genetic library; human subject; human tissue; immunofluorescence technique; immunoprecipitation; insect poison; laboratory rabbit; megakaryocytes; molecular cloning; monomer; pertussis toxin; phorbols; phospholipase A2; phospholipase C; phosphorylation; platelet activation; platelets; polymerase chain reaction; posttranslational modifications; protein kinase C; protein structure function; receptor; second messengers; stoichiometry; terpene saponin; thrombin; tissue /cell culture; western blottings

This proposal will examine the structure and function of a 40 kDa protein in platelets which we believe to be the alpha subunit of a guanine nucleotide-binding regulatory protein or G protein. Based upon our recent studies, this protein has several novel properties. First, it is phosphorylated during platelet activation, apparently by protein kinase C. Second, it is immunologically cross-reactive with G(z-alpha), a putative alpha subunit that has been cloned from two non-platelet cDNA libraries, but not yet isolated. Third, in contrast to the other G proteins which have been a focus for platelet research, it is neither ADP-ribosylated by pertussis toxin nor recognized by antisera that are specific for known pertussis toxin-sensitive G proteins, such as G(i-alpha). Even though G(z- alpha) is not known to be a substrate for protein kinase C, we have provisionally named the platelet protein "G(z-alpha)(plt)" in acknowledgement of the immunologic cross-reactivity of the two proteins. The goal of our studies will be to understand the structure and biology of G(z-alpha)(plt). Specifically, we will: (1) determine the identity of G(z- alpha)(plt) and define its relationship to G(z-alpha), (2) identify the sites at which G(z-alpha)(plt) is phosphorylated, (3) determine the biochemical consequences of phosphorylation and (4) define the role of G(z- alpha)(plt) in platelet function.

该提案将检查 40 kDa 蛋白质的结构和功能 在血小板中，我们认为它是鸟嘌呤的α亚基 核苷酸结合调节蛋白或G蛋白。根据我们最近的 研究表明，这种蛋白质具有多种新特性。首先，它是 在血小板活化过程中磷酸化，显然是由蛋白激酶 C 磷酸化。 其次，它与 G(z-alpha) 发生免疫交叉反应，G(z-alpha) 是一种假定的 已从两个非血小板 cDNA 文库克隆的 α 亚基， 但尚未隔离。第三，与其他 G 蛋白相比， 一直是血小板研究的焦点，它既不是 ADP 核糖基化的 百日咳毒素也不被已知特异性的抗血清识别 百日咳毒素敏感 G 蛋白，例如 G(i-alpha)。即使 G(z- α) 不知道是蛋白激酶 C 的底物，我们有 血小板蛋白暂时命名为“G(z-alpha)(plt)” 承认两种蛋白质的免疫交叉反应性。 我们研究的目标是了解结构和生物学 G(z-α)(plt)。具体来说，我们将： (1) 确定 G(z- alpha)(plt) 并定义其与 G(z-alpha) 的关系，(2) 识别 G(z-alpha)(plt) 被磷酸化的位点，(3) 确定 磷酸化的生化后果和（4）定义了 G(z- 血小板功能中的α)(plt)。