Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB2 9SB, UK.
J Neuroendocrinol. 1990 Dec 1;2(6):773-6. doi: 10.1111/j.1365-2826.1990.tb00639.x.
Bordetella pertussis toxin (islet activating protein, IAP) has been used to investigate the G-proteins involved in mediating the action of the melatonin receptor. Melatonin inhibits iorskolin-stimulated cyclic AMP production in ovine pars tuberalis (PT) cells. In cells treated with IAP for 16 h this response is attenuated in a dose-dependent manner, but not abolished. IAP catalyses the incorporation of [(32) P-ADP]ribose into a 41 kd protein present in PT membranes, but this labelling can be reduced if PT cells are preincubated with IAP for 16 h. Treatment of crude membrane preparations with IAP (20 /ig/ml) suppresses the binding of 2-[(125) l]iodomelatonin by 20%, whereas 1 mM GTP alone reduces binding by 40%, and in combination with IAP its effect is additive (60% inhibition). Therefore, these results indicate that the melatonin receptor acts via two G-proteins, one pertussis toxin-sensitive and the other pertussis toxin-insensitive.
百日咳博德特氏菌毒素（胰岛激活蛋白，IAP）已被用于研究参与调节褪黑素受体作用的 G 蛋白。褪黑素抑制绵羊垂体内分泌部（PT）细胞中异硫氰酸肌醇刺激的环 AMP 产生。用 IAP 处理 16 小时后，这种反应以剂量依赖的方式减弱，但没有被完全消除。IAP 催化 [(32)P-ADP] 核糖掺入 PT 膜中存在的 41 kd 蛋白，但如果 PT 细胞预先用 IAP 处理 16 小时，则可以减少这种标记。用 IAP（20 /ig/ml）处理粗膜制剂可抑制 2-[(125)I]碘褪黑素的结合，抑制率为 20%，而单独使用 1 mM GTP 可降低结合率 40%，与 IAP 联合使用时，其作用呈相加性（抑制 60%）。因此，这些结果表明，褪黑素受体通过两种 G 蛋白发挥作用，一种对百日咳毒素敏感，另一种对百日咳毒素不敏感。
