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

The recognition and transport mechanism of ions in the proton pump and its intracellular transport

质子泵中离子的识别和运输机制及其细胞内运输

基本信息

批准号：
10470007
负责人：
TAKEGUCHI Noriaki
金额：
$ 5.76万
依托单位：
TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The main objects of the present research project are to study the recognition and transport mechanisms of K^+ and H^+ ions in the gastric proton pump and its intracellular transport. The pump consists of α-and β-subunits. First, we explored the binding site of SCH 28080 which is a K^+ competitive inhibitor and found that the previously proposed site by others was wrong and the amino acid residues in transmembrane segment 6 of the α subunit of the pump are involved in SCH 28080 binding. From our chimera study between proton pump and Na pump, we found that the amino acid residues in transmembrane segment 6 are involved in K^+ and H^+ recognition. Glu in the transmembrane segment 4 is involved in K^+ binding and the K^+ -dependent conformational change of the α subunit. we also explored the role of the βsubunit of the pump. We found that the four consecutive amino acid sequence located just outside the extracellular part of the membrane has the proton pump destination signal in the cell. Carbohydrate chains in this subunit also has the destination signal and involved in the enzyme activity of the pump. The extracellular S-S cross links in the β-subunit had the important role in the enzyme reaction. The apical cell surface of the gastric parietal cell must, have a protective mechanism against the strong acid secreted by the cell itself. As a possible machinery for this end, we found the presence of a flippase, which can secrete both phosphatidylcholine and phosphatidylserine. The secreted phospholipids may serve as a hydrophopbic lining and rejects acid.

本课题的主要目的是研究胃质子泵对K^+和H^+的识别和转运机制及其细胞内转运。该泵由α-和β-亚基组成。首先，我们对K^+竞争性抑制剂SCH 28080的结合位点进行了研究，发现之前有人提出的结合位点是错误的，SCH 28080的结合位点与泵α亚基跨膜段6的氨基酸残基有关。在质子泵和钠泵的嵌合体研究中，我们发现跨膜片段6中的氨基酸残基参与了K^+和H^+的识别。跨膜片段4中的Glu参与K^+结合和α亚基的K^+依赖性构象变化。我们还探索了泵的β亚基的作用。我们发现，位于细胞膜细胞外部分的四个连续氨基酸序列具有细胞中的质子泵目的地信号。碳水化合物链中的这个亚基也具有目的地信号和参与酶活性的泵。β-亚基中的胞外S-S交联在酶反应中起重要作用。胃壁细胞的顶端细胞表面一定有一种保护机制，可以抵抗细胞自身分泌的强酸。作为一种可能的机制，我们发现了翻转酶的存在，它可以分泌磷脂酰胆碱和磷脂酰丝氨酸。分泌的磷脂可以作为一个抗氧化剂衬里和拒绝酸。