The role of the extracellular loops of the CGRP receptor, a family B GPCR
The role of the extracellular loops of the CGRP receptor, a family B GPCR
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DOI：
10.1042/bst20110726
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发表时间：
2012-04-01
影响因子：
3.9
通讯作者：
Poyner, David R.
中科院分区：
文献类型：
--
作者：
Barwell, James;Woolley, Michael J.;Poyner, David R.
CGRP（降钙素基因相关肽）受体是家族B GPCR（G蛋白偶联受体）。它由GPCR、降钙素受体样受体（calcitonin receptor-like receptor）和辅助蛋白RAMP 1（receptor activity-modifying protein 1）组成。RAMP 1是CGRP结合所必需的，也是CUR的细胞表面表达所必需的。对B家族GPCR的ECL（胞外环）的系统研究很少。然而，它们可能对于作为这些受体的天然激动剂的肽激动剂的N-末端的相互作用特别重要。我们已经进行了丙氨酸扫描的所有三个ECL的的，以及它们相关的质膜区域。所有三个环内的残基影响CGRP结合和受体活化。ECL 1上Ala（203）和Ala（206）突变为亮氨酸可增加CGRP的亲和力。TM（跨膜）螺旋2和3顶部的残基影响CGRP结合和受体活化。TM 6/ECL 3中的L351 A和E357 A降低受体表达，并且可能是与RAMP 1 ECL 2结合所需的，这似乎对CGRP功能特别重要;在该环中迄今为止检查的16个残基中，当突变为丙氨酸时，8个残基降低CGRP刺激cAMP产生的效力。
The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity-modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CUR. There have been few systematic studies of the ECLs (extracellular loops) of family B GPCRs. However, they are likely to be especially important for the interaction of the N-termini of the peptide agonists that are the natural agonists for these receptors. We have carried out alanine scans on all three ECLs of CLR, as well as their associated juxtamembrane regions. Residues within all three loops influence CGRP binding and receptor activation. Mutation of Ala(203) and Ala(206) on ECL1 to leucine increased the affinity of CGRP. Residues at the top of TM (transmembrane) helices 2 and 3 influenced CGRP binding and receptor activation. L351A and E357A in TM6/ECL3 reduced receptor expression and may be needed for CLR association with RAMP1 ECL2 seems especially important for CLR function; of the 16 residues so far examined in this loop, eight residues reduce the potency of CGRP at stimulating cAMP production when mutated to alanine.