Localization of agonist- and antagonist-binding domains of human corticotropin-releasing factor receptors.
Localization of agonist- and antagonist-binding domains of human corticotropin-releasing factor receptors.
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DOI：
10.1210/mend.11.13.0034
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发表时间：
1997-12
影响因子：
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通讯作者：
Chen W. Liaw;D. Grigoriadis;M. Lorang;E. B. D. Souza;Richard A. Maki
中科院分区：
文献类型：
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作者：
Chen W. Liaw;D. Grigoriadis;M. Lorang;E. B. D. Souza;Richard A. Maki
CRF受体CRFR1和CRFR2是G蛋白偶联受体超家族的成员。尽管它们具有相当大的序列相似性，但CRFR1和CRFR2对肽配体大鼠/人CRF具有完全不同的亲和力。先前使用人CRFR1和CRFR2之间嵌合受体的研究已经确定了CRF受体的第二和第三细胞外结构域的三个潜在重要区域与大鼠/人CRF结合。本报告进一步表明，这三个区域也影响尿皮质素和索瓦蛋白（CRF肽家族的另外两个成员）的结合，尽管程度不同。我们还发现，第三个细胞外结构域的第四个区域Asp254对sauvagine很重要，但对CRF或尿皮质素结合不起作用。因此，这三种肽配体不仅与CRFR1和CRFR2上的一组不同区域相互作用，而且与一些相同区域的相互作用存在差异。与大鼠/人CRF相比，这些数据至少可以部分解释CRFR2对尿皮质素和索瓦菌素的亲和力要高得多。我们还发现了两个氨基酸残基，位于第三跨膜结构域的His199和位于第五跨膜结构域的Met276，它们对于结合非肽高亲和力CRFR1拮抗剂NBI 27914非常重要。His199和Met276对CRFR2中相应氨基酸的突变分别使NBI 27914对CRFR1的结合亲和力降低了40倍和200倍。这表明跨膜区域对于形成非肽拮抗剂的结合袋至关重要。
The CRF receptors, CRFR1 and CRFR2, are members of the G protein-coupled receptor superfamily. Despite their considerable sequence similarity, CRFR1 and CRFR2 have quite different affinities for the peptide ligand rat/human CRF. Previous studies using chimeric receptors between human CRFR1 and CRFR2 have identified three potentially important regions in the second and third extracellular domains of CRF receptor for the binding of rat/human CRF. The present report further demonstrates that these same three regions also affect the binding of urocortin and sauvagine, two other members of the CRF peptide family, albeit to different extents. We also show that a fourth region in the third extracellular domain, Asp254, has been identified to be important for sauvagine but not CRF or urocortin binding. Thus, the three peptide ligands not only interact with a different set of regions on CRFR1 and CRFR2 but also differentially interact with some of the same regions. These data could, at least in part, account for the much higher affinity of CRFR2 for urocortin and sauvagine compared with rat/human CRF. We have also identified two amino acid residues, His199 in the third transmembrane domain and Met276 in the fifth transmembrane domain, that are important for binding the non-peptide high-affinity CRFR1 antagonist NBI 27914. Mutations of His199 and Met276 to the corresponding amino acids in CRFR2 each decreased the binding affinity of NBI 27914 for CRFR1 by 40- and 200-fold, respectively. This suggests that the transmembrane regions are critically important in forming the binding pocket for the nonpeptide antagonist.