权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

PGI & TXA SYNTHASES--MEMBRANE ANCHOR STRUCTURE/FUNCTION

前列腺素I

基本信息

批准号：
6043919
负责人：
KE-HE RUAN
金额：
$ 10.14万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
1996
资助国家：
美国
起止时间：
1996-08-01 至 2000-07-31
项目状态：
已结题

项目摘要

DESCRIPTION: (Adapted from Applicant's Abstract) This is a FIRST award application from Dr. Ke-He Ruan. The title of the project is PGI & TXA Synthases: Membrane Anchor Structure/Function. Prostaglandin H2 (PGH2) is converted to Prostaglandin I2 (PGI2) via the catalytic action of Prostaglandin I2 synthase (PGIS). PGI2 is a vasodilator and inhibitor of platelet function. It recently has been employed intravenously for the treatment of pulmonary hypertension. An eicosanoid with actions as a platelet agonist and vasoconstrictor is thromboxane A2 (TXA2). TXA2 also forms from PGH2, via another enzyme, thromboxane A2 synthase (TXAS), a member of the cytochrome P450 superfamily. The structure and function of the N-terminal membrane anchor domains of PGIS and TXAS have not been clearly elucidated. Dr. Ruan has found that TXAS has two separate N-terminal anchor segments and the N- terminus itself faces the cytosol. In contrast, PGIS has 16% sequence identity with TXAS and the hydropathy profile in the N- terminal domain is different. Dr. Ruan suggests that the PGIS membrane anchor structure and the PGIS spatial orientation in relation to the membrane may be different from TXAS. PGH2 is synthesized in the lumen of the endoplasmic reticulum and therefore, the orientation of PGIS and TXAS active sites in relation to the membrane may be important for their conversion of PGH2 into biochemically active eicosanoids with different effects. Other results have shown that the substrate access channel of TXAS faces the ER membrane with the same orientation of the N-terminal membrane anchor region. In this project, attempts will be made to understand how the cytochrome P450 enzymes control eicosanoid biosynthesis. Techniques will include peptidoliposome reconstitution, anti-peptide antibodies which are site- specific, immunocytochemistry, circular dichroism studies, molecular modeling and NMR spectroscopy. The membrane interactions of the N-terminal anchor domains of PGIS and TXAS will be characterized. They will be compared with other cytochrome P450 enzymes in microsomes. The topological arrangement of the catalytic portion of PGIS will be identified in the membrane and it will be compared to that of TXAS. This will also include the determination of the 3D structures of the N-terminal membrane anchor domains of PGIS and TXAS. These will be compared with other microsomal P450s. The residues involved with substrate channel entrance in TXAS and PGIS will be identified. The topological relationship between the substrate channel opening and the ER membrane will be characterized. The experiments should result in the ability to construct a working model for the arrangement of PGIS and comparison with TXAS in the ER membrane. The information should allow for comprehension of similarities and differences between PGIS and TXAS as they relate to the ER membrane and how they coordinate with PGH synthase. Comparisons can then be made between the membrane anchor structure of these two eicosanoid-forming P450s and the anchor structures of other microsomal P450s.

描述：（改编自申请人的摘要）这是第一个奖项阮科和医生的申请。该项目的标题是PGI & TXA 合成酶：膜锚结构/功能。前列腺素H2 （PGH 2）通过催化作用转化为前列腺素I2（PGI 2）前列腺素I2合酶（PGIS）。 PGI 2是血管扩张剂和抑制剂血小板功能。它最近被用于静脉注射，肺动脉高压的治疗一种具有行动的类花生酸作为血小板激动剂和血管收缩剂的是血栓素A2（TXA 2）。 TXA 2也通过另一种酶血栓烷A2由PGH 2形成 TXAS是细胞色素P450超家族的成员。的 N-末端膜锚结构域的结构和功能 PGIS和TXAS尚未明确阐明。阮医生发现 TXAS具有两个独立的N-末端锚段和N-末端锚段，末端本身面向胞质溶胶。相比之下，PGIS有16% 与TXAS的序列同一性和N-甲基-N- 终端域不同。阮博士认为PGIS膜锚结构和PGIS空间方向与膜可能与TXAS不同。 PGH 2是在内质网的内腔，因此，与膜相关的PGIS和TXAS活性位点可能是对于它们将PGH 2转化为生物化学活性具有不同效果的类花生酸。其他结果表明， TXAS的底物进入通道面向ER膜， N-末端膜锚区的取向相同。在这个项目中，将试图了解细胞色素 P450酶控制类花生酸的生物合成。技术将包括肽脂质体重建，抗肽抗体，这是网站- 特异性，免疫细胞化学，圆二色性研究，分子建模和NMR光谱。膜的相互作用将表征PGIS和TXAS的N-末端锚结构域。它们将与其他细胞色素P450酶进行比较，微粒体催化部分的拓扑排列将在膜中识别PGIS，并与关于TXAS 这也将包括确定3D PGIS的N-末端膜锚结构域的结构， TXAS。这些将与其他微粒体P450进行比较。的 TXAS和PGIS中参与底物通道入口的残基将被识别。的拓扑关系。将表征基质通道开口和ER膜。实验应导致构建工作的能力 PGIS在ER中的布置模型及其与TXAS的比较膜的这些信息应允许理解 PGIS和TXAS之间的异同，因为它们涉及到 ER膜以及它们如何与PGH合酶协调。比较然后可以在这两个膜锚结构之间制成类花生酸形成P450和其他微粒体的锚结构 P450