Enhancement of the Ca2+-triggering steps of native membrane fusion via thiol-reactivity

Journal of Chemical Biology

David M. Brandman²  Kendra L. Furber¹  Jens R. Coorssen³ 

[1] Hotchkiss Brain Institute, University of Calgary Faculty of Medicine, Calgary, AB T2N 4N1 Canada;Department of Physiology and Biophysics, University of Calgary Faculty of Medicine, Calgary, AB T2N 4N1 Canada;Molecular Physiology, School of Medicine, University of Western Sydney, Bldg. 30, Campbelltown, NSW 1797 Australia

关键词: Membrane fusion;    Calcium;    Strontium;    Thiol reactivity;    Exocytosis;    Vesicle;   

DOI  :  10.1007/s12154-008-0013-3

学科分类：分子生物学，细胞生物学和基因

来源: Springer

【 摘 要 】

Ca2+-triggered membrane fusion is the defining step of exocytosis. Isolated urchin cortical vesicles (CV) provide a stage-specific preparation to study the mechanisms by which Ca2+ triggers the merger of two apposed native membranes. Thiol-reactive reagents that alkylate free sulfhydryl groups on proteins have been consistently shown to inhibit triggered fusion. Here, we characterize a novel effect of the alkylating reagent iodoacetamide (IA). IA was found to enhance the kinetics and Ca2+ sensitivity of both CV-plasma membrane and CV–CV fusion. If Sr2+, a weak Ca2+ mimetic, was used to trigger fusion, the potentiation was even greater than that observed for Ca2+, suggesting that IA acts at the Ca2+-sensing step of triggered fusion. Comparison of IA to other reagents indicates that there are at least two distinct thiol sites involved in the underlying fusion mechanism: one that regulates the efficiency of fusion and one that interferes with fusion competency.

【 授权许可】

Unknown