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To explore the molecular basis of ligand binding and receptor activation of human motilin receptor

探讨人胃动素受体配体结合和受体激活的分子基础

基本信息

批准号：
16590599
负责人：
MATSUURA Bunzo
金额：
$ 2.24万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16590599/
关键词：
motilin receptor motilin erythromycin ghrelin

项目摘要

Background. Motilin and ghrelin have been recognized as important endogenous regulators of gastrointestinal (GI) motor function in mammals, mediated by the motilin receptor and by the closely-related growth hormone secretagogue (GHS) receptor, respectively. The aims of this study were to identify the ligand-binding sites within the human motilin receptor, and to explore the distribution of motilin and GHS receptors along the human gastrointestinal tract, and to establish the molecular nature of the human motilin receptor. Methods. We examined the extracellular domains of the human motilin receptor using the methods of receptor mutagenesis and photoaffinity labeling. We also analyzed levels of expression of mRNA and immunoreactivity for motilin and GHS receptors in the human GI tract. Results. Cys residues in the amino terminus and the first and second extracellular loop domains in the motilin receptor, Cys25, Cys30, Cys111, and Cys235, are critical for both peptide ligand, motilin, and non-peptidyl ligand, erythromycin, biological activities, conserving the disulfide bond in this receptor. The perimembranous residues, Gly36, Pro103, Leu109, and Phe332, are important only for binding and biological activity of peptide ligand. The long form of the motilin receptor, but not the short form, was expressed in all parts of the GI tract, and expressed at higher levels in muscle than in mucosa. Motilin receptor immunoreactivity was present on muscle cells and myenteric plexus. In contrast, GHS receptor mRNA and immunoreactivity were expressed equally in both mucosal and muscle layers in all parts of GI tract. Conclusions. These results, suggest that differential contribution of motilin receptor extracellular domains for peptide ligand and non-peptidyl ligand binding and action, and the diffuse muscle expression of the motilin receptor along the entire GI tract make it a useful potential target for motilide drugs for dysmotility.

背景胃动素和生长激素释放肽被认为是哺乳动物胃肠运动功能的重要内源性调节因子，分别由胃动素受体和密切相关的生长激素促分泌素（GHS）受体介导。本研究的目的是鉴定人胃动素受体的配体结合位点，并探讨胃动素和GHS受体沿着人胃肠道的分布，以确定人胃动素受体的分子性质。方法.我们用受体突变和光亲和标记的方法研究了人胃动素受体的胞外区。我们还分析了人胃肠道中胃动素和GHS受体的mRNA表达水平和免疫反应性。结果胃动素受体中氨基末端和第一和第二胞外环结构域中的Cys残基Cys25、Cys30、Cys111和Cys235对于肽配体胃动素和非肽基配体红霉素的生物活性都是至关重要的，从而保存了该受体中的二硫键。膜周残基Gly36、Pro103、Leu109和Phe332仅对肽配体的结合和生物活性重要。胃动素受体的长型，而不是短型，在胃肠道的所有部分中表达，并且在肌肉中的表达水平高于粘膜。胃动素受体免疫反应性存在于肌细胞和肌间神经丛。相反，GHS受体mRNA和免疫反应性在胃肠道的所有部分的粘膜层和肌肉层中表达相等。结论.这些结果表明，胃动素受体胞外结构域对肽配体和非肽基配体结合和作用的不同贡献，以及胃动素受体沿着整个胃肠道的弥漫性肌肉表达，使其成为胃动素药物治疗运动障碍的有用的潜在靶点。