Structure and Functions of CD38

CD38的结构和功能

• 批准号: 7028076
• 负责人: RICHARD M GRAEFF
• 金额: $ 41.85万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7028076
• 关键词: CD38 molecule; NAD(H) analog; NAD(H) phosphate; adenosine diphosphate; biological signal transduction; calcium; calcium flux; catalyst; inositol phosphates; nucleic acid chemical synthesis

DESCRIPTION (provided by applicant): It is generally believed that multiple Ca2+ stores are present in cells, a notion that has now been made substantive by the discovery of multiple Ca2+ mobilizing messengers. Cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) are two such messengers that are derived from NAD and NADP, respectively. A wide variety of cells, from plants to mammals, including human, have been shown to be responsive to these two novel Ca2+ messengers. Not only are their structures and mechanisms of action different, their targeted Ca2+ stores are also distinct and separable. Moreover, they are derived from different substrates, cADPR from NAD and NAADP from NADP. It is thus entirely unexpected that a single enzyme is responsible for synthesizing these two different Ca2+-messengers. CD38 is one such enzyme and it belongs to a new family of homologues that includes CD157 and Aplysia ADP-ribosyl cyclase. Results using knockout mice show that CD38 is the most dominant enzyme in mammalian tissues responsible for synthesizing cADPR and NAADP. The emerging view is that cADPR and NAADP represent two branches of a novel Ca2+-signaling pathway with CD38 at its bifurcation point. Because of its pivotal role in the cADPR/NAADP-signaling pathway, it is of critical importance that the molecular mechanism of its action be elucidated. We have expressed the extra-membrane domain of CD38 in yeast as a soluble protein that retains all enzymatic activities indistinguishable from native CD38. We have mapped the active site and identified the critical residues in it by site-directed mutagenesis. These results form the basis for a unified catalytic model that accounts for the novel multiplicity of this family of signaling enzymes. We have now succeeded in crystallizing CD38 and solved its structure. The structure-function studies described in this proposal will verify and refine the catalytic model and the specific aims are: Aim 1: To determine the structural basis of the multi-catalytic functions of CD38. Aim 2: To determine the structural basis of regulation of CD38 catalysis. Aim 3: To determine the structural basis of the antigenic functions of CD38. Aim 4: To characterize intracellular CD38.

描述（由申请人提供）：通常认为，单元格中存在多个Ca2+存储，这一概念已通过发现多个CA2+动员Messenger而实现。环状ADP-核糖（CADPR）和烟酸腺嘌呤二核苷酸磷酸盐（NAADP）分别是两个源自NAD和NADP的使者。从植物到哺乳动物（包括人）的各种细胞已被证明对这两个新型CA2+信使有反应。它们的作用结构和机制不仅不同，其目标CA2+商店也是独特的且可分开的。此外，它们源自不同的底物，来自NAD的CADPR和NADP的NAADP。因此，单个酶负责综合这两个不同的Ca2+m肌者，这是完全出乎意料的。 CD38就是一种这样的酶，它属于包括CD157和Aplysia adp-ribosyl Cyclase在内的新型同源物系列。使用基因敲除小鼠的结果表明，CD38是负责合成CADPR和NAADP的哺乳动物组织中最优势的酶。新兴的观点是，CADPR和NAADP代表了新型Ca2+信号途径的两个分支，其分叉点具有CD38。由于其在CADPR/NAADP信号途径中的关键作用，因此阐明其作用的分子机制至关重要。我们已经表达了酵母中CD38的膜外域，是一种可溶性蛋白，它保留了与天然CD38无法区分的所有酶促活性。我们已经绘制了活性位点，并通过位于位置的诱变确定了其中的关键残基。这些结果构成了统一的催化模型的基础，该模型解释了这种信号酶家族的新型多样性。现在，我们已经成功地结晶了CD38并解决了其结构。本提案中描述的结构功能研究将验证和完善催化模型，具体目的是： 目标1：确定CD38多催化功能的结构基础。 目标2：确定CD38催化调节的结构基础。 目标3：确定CD38抗原功能的结构基础。 目标4：表征细胞内CD38。