Yasuda K, Seino Y
Kyoto University Faculty of Integrated Human Studies.
Nihon Rinsho. 1996 Apr;54(4):1078-82.
Gastric inhibitory polypeptide, originally isolated from porcine intestine, is a gastrointestinal hormone belonging to the vasoactive intestinal peptide (VIP)/glucagon/secretin family. GIP consists of 42 amino acid residues which is derived by proteolytic processing of a GIP precursor. In vivo and in vitro experiments have indicated that GIP auguments glucose-stimulated insulin secretion, suggesting that GIP plays an important role in the regulation of insulin secretion as an incretin. Thus, GIP now is generally referred to as glucose-dependent insulinotropic polypeptide. It is also suggested that GIP may be involved in the pathogenesis of non insulin-dependent diabetes mellitus (NIDDM). GIP exerts its biological actions by binding to its specific receptors, which appear to be coupled to G proteins. We have isolated a cDNA encoding a GIP receptor from a hamster insulinoma(HIT-T15) cDNA library. The hamster GIP receptor is a 462 amino acid protein having seven transmembrane segments. Expression of recombinant of hamster GIP receptors in Chinese hamster ovary (CHO) cells shows that it binds specifically to GIP with high affinity (IC50 = 9.6 nM) and is positively coupled to adenylate cyclase. RNA blot analysis reveals that a 3.8-kb GIP receptor mRNA is expressed at high levels in rat pancreatic islets as well as in HIT-T15 cells.
胃抑制性多肽最初是从猪肠道中分离出来的，是一种属于血管活性肠肽（VIP）/胰高血糖素/促胰液素家族的胃肠激素。胃抑制性多肽由42个氨基酸残基组成，它是由胃抑制性多肽前体经蛋白水解加工而成。体内和体外实验表明，胃抑制性多肽能增强葡萄糖刺激的胰岛素分泌，这表明胃抑制性多肽作为一种肠促胰岛素在胰岛素分泌调节中起重要作用。因此，胃抑制性多肽现在通常被称为葡萄糖依赖性促胰岛素多肽。也有人提出胃抑制性多肽可能参与非胰岛素依赖型糖尿病（NIDDM）的发病机制。胃抑制性多肽通过与其特异性受体结合发挥其生物学作用，这些受体似乎与G蛋白偶联。我们从仓鼠胰岛素瘤（HIT-T15）cDNA文库中分离出一个编码胃抑制性多肽受体的cDNA。仓鼠胃抑制性多肽受体是一种含有7个跨膜区段的462个氨基酸的蛋白质。在中国仓鼠卵巢（CHO）细胞中重组表达仓鼠胃抑制性多肽受体表明，它能以高亲和力（IC50 = 9.6 nM）特异性结合胃抑制性多肽，并与腺苷酸环化酶呈正偶联。RNA印迹分析显示，一个3.8 kb的胃抑制性多肽受体mRNA在大鼠胰岛以及HIT-T15细胞中高水平表达。
