Dual effects of G‐protein activation on Ca‐dependent exocytosis in bovine lactotrophs

FEBS Letters

Zorec, R.¹  Brown, D.²  Mason, W.T.²  Sikdar, S.K.² 

[1] Institute of Pathophysiology, 61105 Ljubljana, Yugoslavia;Department of Neuroendocrinology, AFRC Institute of Animal Physiology & Genetics Research, Babraham, Cambridge CB2 4AT, England

关键词: Ca2+;    intracellular;    G-protein;    GTP analog;    Exocytosis;    Prolactin;    Patch clamp;   

DOI  :  10.1016/0014-5793(89)80936-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The whole-cell patch-clamp technique was used to measure cell membrane capacitance (C _m) to monitor exocytosis in single-cultured bovine prolactin-secreting cells (lactotrophs) of the anterior pituitary. The cells were dialyzed with solutions containing different concentrations of ionised Ca and non-hydrolyzable GTP analogues (GTP-γ-S and GMP-PNP) to activate G-proteins. We have identified two distinct effects of G-protein activation on Ca-induced exocytosis: (i) the maximum C _m increase due to intracellular Ca-dependent exocytosis was diminished, suggesting an inhibitory role of G-proteins close to the site of granule fusion, while (ii) the rate of C _m increase (ΔC _m/Δt) was facilitated, revealing conversely a stimulatory role of G-proteins in the translocation of secretory granules to the fusion sites.

【 授权许可】

Unknown