Liu Rongfang, van Veldhoven Jacobus P D, IJzerman Adriaan P
Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Eur J Pharmacol. 2016 Jan 5;770:70-7. doi: 10.1016/j.ejphar.2015.11.052. Epub 2015 Dec 4.
In the present study we focused our attention on the family of hydroxycarboxylic acid (HCA) receptors, a GPCR family of three members, of which the HCA2 and HCA3 receptors share 95% high sequence identity but differ considerably in C-terminus length with HCA3 having the longest tail. The two receptors were expressed and analysed for their activation profile in Saccharomyces cerevisiae MMY yeast strains that have different G protein Gα subunits. The hHCA2 receptor was promiscuous in its G protein coupling preference. In the presence of nicotinic acid the hHCA2 receptor activated almost all G protein pathways except Gαq (MMY14). However, the Gα protein coupling profile of the hHCA3 receptor was less promiscuous, as the receptor only activated Gαi1 (MMY23) and Gαi3 (MMY24) pathways. We then constructed two mutant receptors by 'swapping' the short (HCA2) and long (HCA3) C-terminus. The differences in HCA2 and HCA3 receptor activation and G protein selectivity were not controlled, however, by their C-terminal tails, as we observed only minor differences between mutant and corresponding wild-type receptor. This study provides new insights into the G protein coupling profiles of the HCA receptors and the function of the receptor's C terminus, which may be extended to other GPCRs.
在本研究中，我们将注意力集中在羟基羧酸（HCA）受体家族上，这是一个由三个成员组成的G蛋白偶联受体（GPCR）家族，其中HCA2和HCA3受体具有95%的高序列同一性，但C末端长度差异很大，HCA3的尾巴最长。在具有不同G蛋白Gα亚基的酿酒酵母MMY酵母菌株中表达这两种受体，并分析它们的激活谱。人源HCA2受体在G蛋白偶联偏好方面较为混杂。在烟酸存在的情况下，人源HCA2受体几乎激活了除Gαq（MMY14）之外的所有G蛋白途径。然而，人源HCA3受体的Gα蛋白偶联谱则不那么混杂，因为该受体仅激活Gαi1（MMY23）和Gαi3（MMY24）途径。然后，我们通过“交换”短的（HCA2）和长的（HCA3）C末端构建了两个突变受体。然而，HCA2和HCA3受体激活及G蛋白选择性的差异并非由它们的C末端尾巴所控制，因为我们在突变体和相应野生型受体之间仅观察到微小差异。本研究为HCA受体的G蛋白偶联谱以及受体C末端的功能提供了新的见解，这些见解可能扩展到其他GPCR。
