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Most Synaptic Vesicles Isolated from Rat Brain Carry Three Membrane Proteins, SV2, Synaptophysin, and p65
Author(s) -
Floor E.,
Feist B. E.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb09190.x
Subject(s) - synaptophysin , synaptic vesicle , vesicle , exocytosis , vesicle fusion , snap25 , biology , microbiology and biotechnology , ficoll , chemistry , biophysics , membrane , biochemistry , immunology , immunohistochemistry , peripheral blood mononuclear cell , in vitro
We have prepared highly purified synaptic vesicles from rat brain by subjecting vesicles purified by our previous method to a further fractionation step, i.e., equilibrium centrifugation on a Ficoll gradient. Monoclonal antibodies to three membrane proteins enriched in synaptic vesicles—SV2, synaptophysin, and p65—each were able to immunoprecipitate specifically ∼90% of the total membrane protein from Ficoll‐purified synaptic vesicle preparations. Anti‐SV2 precipitated 96% of protein, anti‐synaptophysin 92%, and antip65 83%. These results demonstrate two points: (1) Ficollpurified synaptic vesicles appear to be >90% pure, i.e., < 10% of membranes in the preparation do not carry synaptic vesicleassociated proteins. These very pure synaptic vesicles may be useful for direct biochemical analyses of mammalian synaptic vesicle composition and function. (2) SV2, synaptophysin, and p65 coexist on most rat brain synaptic vesicles. This result suggests that the functions of these proteins are common to most brain synaptic vesicles. However, if SV2, synaptophysin, or p65 is involved in synaptic vesicle dynamics, e.g., in vesicle trafficking or exocytosis, separate cellular systems are very likely required to modulate the activity of such proteins in a temporally or spatially specific manner.