Ohara-Imaizumi M, Takeda K, Kawae N, Kumakura K
Life Science Institute, Sophia University, Tokyo, Japan.
Neurosci Lett. 1990 Mar 2;110(1-2):167-71. doi: 10.1016/0304-3940(90)90806-k.
Effects of pertussis toxin (islet-activating protein, IAP) on the secretory function of bovine adrenal chromaffin cells in culture were studied. Treatment of chromaffin cells with IAP resulted in an increase in both basal release of catecholamine and evoked-release by either acetylcholine (ACh) or high K+. In the dose-response curve for ACh-evoked release, IAP treatment produced an increase of the maximal response without affecting the half-maximal concentration of ACh. When the cells were permeabilized with digitonin after IAP-pretreatment, Ca2(+)-dependent exocytosis was markedly increased where the affinity of exocytosis for Ca2+ was augmented. These findings suggest that IAP-sensitive GTP-binding protein (or proteins) directory controls the Ca2(+)-triggered process in the machinery of exocytosis by modulating the affinity for Ca2+ of its unknown target.
研究了百日咳毒素（胰岛激活蛋白，IAP）对培养的牛肾上腺嗜铬细胞分泌功能的影响。用IAP处理嗜铬细胞导致儿茶酚胺的基础释放以及由乙酰胆碱（ACh）或高钾离子（K⁺）引起的诱发释放均增加。在ACh诱发释放的剂量反应曲线中，IAP处理使最大反应增加，而不影响ACh的半数最大浓度。在用IAP预处理后用洋地黄皂苷使细胞透化时，Ca²⁺依赖性胞吐作用明显增加，其中胞吐作用对Ca²⁺的亲和力增强。这些发现表明，IAP敏感的GTP结合蛋白直接通过调节其未知靶点对Ca²⁺的亲和力来控制胞吐机制中Ca²⁺触发的过程。
