High potency antagonists of the pancreatic glucagon-like peptide-1 receptor
High potency antagonists of the pancreatic glucagon-like peptide-1 receptor
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DOI：
10.1074/jbc.272.34.21201
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发表时间：
1997-08-22
影响因子：
4.8
通讯作者：
Eng, J
中科院分区：
文献类型：
--
作者：
MontroseRafizadeh, C;Yang, H;Eng, J
GLP-1-（7-36）-酰胺和毒蜥外泌肽-4-（1-39）是胰高血糖素样肽-I（GLP-1）受体激动剂，而毒蜥外泌肽-（9-39）是唯一已知的拮抗剂。为了分析从激动剂到拮抗剂的转变并鉴定参与GLP-1受体的配体活化的氨基酸残基，我们使用具有连续N-末端截短的毒蜥外泌肽类似物，在不存在或存在半数最大刺激剂量的GLP-1的情况下，测定用大鼠GLP-1受体稳定转染的中国仓鼠卵巢细胞中由测试肽引起的细胞内cAMP的变化。单个氨基酸的N-末端截短降低了毒蜥外泌肽的激动剂活性，而3-7个氨基酸的N-末端截短产生了比毒蜥外泌肽-（9-39）有效4-10倍的拮抗剂，GLP-1的N-末端截短2个氨基酸导致弱激动剂活性，但8个氨基酸的N-末端截短使肽失活，使用I-125标记的GLP-1进行的结合研究证实，所有生物活性肽都以高效力特异性地置换示踪剂。在一组毒蜥外泌肽/GLP-1嵌合肽中，GLP-1序列置换为毒蜥外泌肽-（3-39）导致拮抗剂活性丧失，转化为弱激动剂，结果表明，受体结合和激活发生在exendin的不同结构域中，但它们在GLP-1中更紧密地偶联。
GLP-1-(7-36)-amide and exendin-4-(1-39) are glucagon-like peptide-1 (GLP-1) receptor agonists, whereas exendin-(9-39) is the only known antagonist, To analyze the transition from agonist to antagonist and to identify the amino acid residues involved in ligand activation of the GLP-1 receptor, we used exendin analogs with successive N-terminal truncations, Chinese hamster ovary cells stably transfected with the rat GLP-1 receptor were assayed for changes in intracellular cAMP caused by the test peptides in the absence or presence of half-maximal stimulatory doses of GLP-1. N-terminal truncation of a single amino acid reduced the agonist activity of the exendin peptide, whereas N-terminal truncation of 3-7 amino acids produced antagonists that were 4-10-fold more potent than exendin-(9-39), N-terminal truncation of GLP-1 by 2 amino acids resulted in weak agonist activity, but an 8-amino acid N-terminal truncation inactivated the peptide, Binding studies performed using I-125-labeled GLP-1 confirmed that all bioactive peptides specifically displaced tracer with high potency, In a set of exendin/GLP-1 chimeric peptides, substitution of GLP-1 sequences into exendin-(3-39) produced loss of antagonist activity with conversion to a weak agonist, The results show that receptor binding and activation occur in separate domains of exendin, but they are more closely coupled in GLP-1.