Evidence of heterotrimeric G-protein involvement in regulated exocytosis from permeabilized pancreatic acini.
Evidence of heterotrimeric G-protein involvement in regulated exocytosis from permeabilized pancreatic acini.
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异三聚体 G 蛋白参与透化胰腺腺泡胞吐作用调节的证据。
DOI：
10.1097/00006676-199505000-00009
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Howell,GW
中科院分区：
文献类型：
--
作者：
DeLisle,RC;Howell,GW
Constitutive membrane trafficking events are regulated by heterotrimeric G-proteins (G-proteins) in addition to their regulation by small GTP-binding proteins (smgs). Here, we used streptolysin O-permeabilized mouse pancreatic acini and compounds that interact with G-proteins, but not smgs, to examine whether G-proteins are also involved in regulated pancreatic exocytosis. The wasp venom mastoparan (10 [mu] M inhibited by 25-50% amylase release from permeabilized acini stimulated by various combinations of Ca2+, cyclic AMP (cAMP), 12-O-tetradecanoylphorbol 13-acetate, and guanosine (5'-[[gamma]-thio] triphosphate (GTP [gamma] S), while the inactive analogue Mas17 was without effect. Pretreatment of intact acini with pertussis toxin resulted in an~ 30% reduction of amylase secretion from cells subsequently permeabilized and stimulated with calcium and GTP [gamma] S. Pretreatment of intact acini with cholera toxin increased stimulated amylase release by 30% from subsequently permeabilized cells, and this effect was mimicked by 8-Br-cAMP. The cAMP-dependent protein kinase inhibitor H-89 (3 [mu] M) largely reversed the effect of cholera toxin, indicating that cholera toxin's effect is due to increased cellular cAMP levels. The inhibitory effects of mastoparan and pertussis toxin suggest that a Gi/Go-type G-protein (s) is (are) involved in the regulation of exocytosis. Since mastoparan inhibited exocytosis stimulated by all intracellular mediators tested, it indicates that the G-protein acts at a distal step in the exocytic process.
