Olde B, Sabirsh A, Owman C
Department of Physiology and Neuroscience, Wallenberg Neuroscience Center, University of Lund, Sweden.
J Mol Neurosci. 1998 Oct;11(2):127-34. doi: 10.1385/JMN:11:2:127.
Receptors for the neurotransmitter and neuroendocrine peptides, vasoactive intesinal peptide (VIP) and secretin, both belong to the Type B subfamily of G-protein-coupled receptors. This group is evolutionally as well as structurally distinct from the much larger Type A, or rhodopsin-type, subfamily. We have mapped the ligand-activating epitopes of the human VIP1 receptor by the use of hybrid receptor constructs with the human secretin receptor. Twelve chimeras were synthesized the successively replacing portions of the former receptor with corresponding portions of the latter receptor, or by interchanging the first extracellular loops. Each of the different chimeric receptor DNAs were then expressed in murine reporter cells, and their ability to activate cAMP production was investigated on stimulation with the respective natural peptide ligands. We stimulated the reporter cells with secretion or VIP following transient expression of the receptor chimeras. The experiments indicated that there are two molecular domains of importance for the recognition and activation of these peptides, namely, the inner portion of the extracellular tail and the first extracellular loop of the two receptors.
神经递质和神经内分泌肽血管活性肠肽（VIP）及促胰液素的受体均属于G蛋白偶联受体B型亚家族。该亚家族在进化和结构上均与大得多的A型（视紫红质型）亚家族不同。我们通过使用与人促胰液素受体的杂交受体构建体，绘制了人VIP1受体的配体激活表位。合成了12个嵌合体，依次用后者受体的相应部分替换前者受体的部分，或通过交换第一个细胞外环来实现。然后将每个不同的嵌合受体DNA在小鼠报告细胞中表达，并研究它们在用各自天然肽配体刺激时激活环磷酸腺苷（cAMP）产生的能力。在用受体嵌合体瞬时表达后，我们用促胰液素或VIP刺激报告细胞。实验表明，对于这些肽的识别和激活有两个重要的分子结构域，即细胞外尾部的内部和两个受体的第一个细胞外环。
