Exploration of the Endogenous Agonist Mechanism for Activation of Secretin and VPAC1 Receptors Using Synthetic Glycosylated Peptides
Exploration of the Endogenous Agonist Mechanism for Activation of Secretin and VPAC1 Receptors Using Synthetic Glycosylated Peptides
复制标题
DOI：
10.1007/s12031-008-9058-6
复制
发表时间：
2008-11-01
影响因子：
3.1
通讯作者：
Miller, Laurence J.
中科院分区：
文献类型：
--
作者：
Dong, Maoqing;Pinon, Delia I.;Miller, Laurence J.
目前对II类G蛋白偶联受体激活的分子基础的理解仍然有限，尽管最近解决了几个家族成员的氨基末端结构域的NMR和晶体结构。这些受体的激活机制之一是激动剂刺激受体氨基末端构象的变化。这导致在与受体核心相互作用的受体氨基末端内暴露“隐藏的内源性激动剂”（分泌素和VPAC 1受体中的WDN序列），从而改变其构象并暴露其G蛋白结合区。已知该WDN序列中的Asn在分泌素和VPAC 1受体中都被糖基化，这引起了人们对这种翻译后修饰是否可能干扰所提出的机制的关注。因此，我们制备了糖基化形式的环状WDN和较长的环状肽LWDNM，并测试了它们在分泌素和VPAC 1受体携带细胞系中的激动剂活性。两种糖基化肽均刺激细胞系中的完全cAMP应答。显然，糖基化不干扰这种机制，实际上可能有助于内源性激动剂配体药效团的正确定位。这些数据为该受体家族的激活机制提供了进一步的证据。
Current understanding of the molecular basis of activation of class II G protein-coupled receptors remains limited, despite recent solution of NMR and crystal structures of amino-terminal domains of several family members. One mechanism proposed for the activation of these receptors involves an agonist-stimulated change in conformation of the receptor amino terminus. This results in the exposure of a "hidden endogenous agonist" (WDN sequence in secretin and VPAC1 receptors) within the receptor amino terminus that interacts with the receptor core, thereby changing its conformation and exposing its G protein-binding region. The Asn in this WDN sequence is known to be glycosylated in both secretin and VPAC1 receptors, raising concern about whether this posttranslational modification might interfere with the proposed mechanism. Therefore, we prepared glycosylated forms of cyclic WDN and the longer cyclic peptide, LWDNM, and tested them for agonist activity at secretin and VPAC1 receptor-bearing cell lines. Both glycosylated peptides stimulated full cAMP responses in the cell lines. Clearly, glycosylation did not interfere with this mechanism and may actually facilitate the correct orientation of the pharmacophore of the endogenous agonist ligand. These data provide further evidence for this proposed mechanism for the activation of this family of receptors.