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Sea urchin egg preparations as systems for the study of calcium‐triggered exocytosis
Author(s) -
Zimmerberg Joshua,
Coorssen Jens R.,
Vogel Steven S.,
Blank Paul S.
Publication year - 1999
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1999.00015.x
Subject(s) - exocytosis , heterotrimeric g protein , munc 18 , vesicle , vesicle fusion , lipid bilayer fusion , calcium , biology , secretory vesicle , microbiology and biotechnology , chemistry , synaptic vesicle , biochemistry , membrane , g protein , signal transduction , organic chemistry
This paper reviews recent work in our laboratory on the mechanism of calcium‐triggered exocytosis. Upon echinoderm egg fertilization, cortical secretory vesicle exocytosis is massive and synchronous. By combining physiological and molecular analyses with a variety of purified membrane isolates containing secretory vesicles that fuse to the plasma membrane or each other, we have characterized the final steps of this calcium‐triggered exocytosis. Our kinetic analysis led to a functional definition of the fusion complex whose activation by calcium follows Poisson statistics. The properties of this complex are compared with the properties of the heterotrimeric SNARE protein complex that is present in the cortical vesicle system. Our data do not support the hypothesis that this particular heterotrimeric complex is by itself the biological fusogen.