Cormont M, Le Marchand-Brustel Y, Van Obberghen E, Spiegel A M, Sharp G W
Unit 145, National Institute of Health and Medical Research, Faculty of Medicine, Nice, France.
Diabetes. 1991 Sep;40(9):1170-6. doi: 10.2337/diab.40.9.1170.
Galanin, an inhibitor of insulin secretion in pancreatic beta-cells, exerts its multiple effects through mechanisms that are sensitive to pertussis toxin (PTX). G proteins have been characterized in RINm5F cells. By ADP ribosylation and immunoblotting, the alpha-subunits of Gi1, Gi2, Gi3, and two forms of Go were identified, Gi alpha 2 being predominant. As expected from a G protein-linked receptor, GTP and its nonhydrolyzable analogue GTP-gamma-S decreased tracer galanin binding to cell membranes. This resulted from a change in receptor affinity without any modification in the number of sites. Selective antibodies against the COOH-terminal decapeptide of the alpha-subunits of the Gi and Go proteins were used to block G protein interaction before we studied galanin binding. Antibody AS, which selectively recognizes Gi alpha 1 and Gi alpha 2, decreased tracer galanin binding to membranes at concentrations where there were no effects of other antibodies specifically directed against Gi alpha 3 or G alpha o. These data suggest that Gi1 and/or Gi2 interact with the galanin receptor and probably mediate the effects of galanin in pancreatic beta-cells.
甘丙肽是胰腺β细胞中胰岛素分泌的抑制剂，它通过对百日咳毒素（PTX）敏感的机制发挥多种作用。已在RINm5F细胞中对G蛋白进行了表征。通过ADP核糖基化和免疫印迹，鉴定出了Gi1、Gi2、Gi3的α亚基以及两种形式的Go，其中Giα2占主导。正如G蛋白偶联受体所预期的那样，GTP及其不可水解的类似物GTP-γ-S降低了示踪甘丙肽与细胞膜的结合。这是由于受体亲和力的变化，而位点数量没有任何改变。在研究甘丙肽结合之前，使用针对Gi和Go蛋白α亚基的COOH末端十肽的选择性抗体来阻断G蛋白相互作用。选择性识别Giα1和Giα2的抗体AS在其他特异性针对Giα3或Gαo的抗体没有作用的浓度下，降低了示踪甘丙肽与膜的结合。这些数据表明，Gi1和/或Gi2与甘丙肽受体相互作用，并可能介导甘丙肽在胰腺β细胞中的作用。
