Kask K, Berthold M, Kahl U, Nordvall G, Bartfai T
Department of Neurochemistry and Neurotoxicology, Stockholm University, Sweden.
EMBO J. 1996 Jan 15;15(2):236-44.
Galanin, a neuroendocrine peptide of 29 amino acids, binds to Gi/Go-coupled receptors to trigger cellular responses. To determine which amino acids of the recently cloned seven-transmembrane domain-type human galanin receptor are involved in the high-affinity binding of the endogenous peptide ligand, we performed a mutagenesis study. Mutation of the His264 or His267 of transmembrane domain VI to alanine, or of Phe282 of transmembrane domain VII to glycine, results in an apparent loss of galanin binding. The substitution of Glu271 to serine in the extracellular loop III of the receptor causes a 12-fold loss in affinity for galanin. We combined the mutagenesis results with data on the pharmacophores (Trp2, Tyr9) of galanin and with molecular modelling of the receptor using bacteriorhodopsin as a model. Based on these studies, we propose a binding site model for the endogenous peptide ligand in the galanin receptor where the N-terminus of galanin hydrogen bonds with Glu271 of the receptor, Trp2 of galanin interacts with the Zn2+ sensitive pair of His264 and His267 of transmembrane domain VI, and Tyr9 of galanin interacts with Phe282 of transmembrane domain VII, while the C-terminus of galanin is pointing towards the N-terminus of th
甘丙肽是一种由29个氨基酸组成的神经内分泌肽，它与Gi/Go偶联受体结合以触发细胞反应。为了确定最近克隆的七跨膜结构域型人甘丙肽受体的哪些氨基酸参与内源性肽配体的高亲和力结合，我们进行了诱变研究。将跨膜结构域VI的His264或His267突变为丙氨酸，或将跨膜结构域VII的Phe282突变为甘氨酸，会导致甘丙肽结合明显丧失。受体细胞外环III中的Glu271被丝氨酸取代会导致对甘丙肽的亲和力丧失12倍。我们将诱变结果与甘丙肽药效基团（Trp2、Tyr9）的数据以及以细菌视紫红质为模型的受体分子建模相结合。基于这些研究，我们提出了甘丙肽受体中内源性肽配体的结合位点模型，其中甘丙肽的N端与受体的Glu271形成氢键，甘丙肽的Trp2与跨膜结构域VI的His264和His267的锌离子敏感对相互作用，甘丙肽的Tyr9与跨膜结构域VII的Phe282相互作用，而甘丙肽的C端指向th的N端
