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Biochemical and Morphological Comparison of Postsynaptic Densities Prepared from Rat, Hamster, and Monkey Brains by Phase Partitioning
Author(s) -
Gurd James W.,
GordonWeeks Phillip,
Evans W. Howard
Publication year - 1982
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.1471-4159.1982.tb11504.x
Subject(s) - hamster , population , biophysics , cerebral cortex , biology , electron microscope , postsynaptic potential , chemistry , biochemistry , microbiology and biotechnology , receptor , neuroscience , physics , demography , sociology , optics
A new procedure for the preparation of postsynaptic densities (PSDs) is described. A synaptic membrane fraction was homogenized in an aqueous two‐phase polymer system containing Poly(ethylene glycol) 6000 (5% wt/wt) and Dextran T500 (6% wt/wt) containing 1% I‐ o ‐ n ‐octyl‐β‐D‐glucoside. Following a brief centrifugation to separate the phases, highly purified PSDs banded at the interface of the two phases. Using this procedure PSDs have been isolated from rat and hamster cerebral cortex and from the frontal cortex, cerebral cortex, hippocampus, and pooled caudateiputamen regions of Macaca mulatta Rhesus monkeys. The isolated PSDs appeared as curved bars when sectioned or as discs when viewed en face in the electron microscope. The hamster PSDs were associated with large numbers of small rod‐like structures 4.5 nm thick and 28 nm long. Similar structures were present, although in fewer numbers, in the rat and monkey preparations. Polyacrylamide gel electrophoresis showed that the PSDs contained a complex population of proteins with major components having molecular weights of 180,000, 130,000, 110,000, 94,000, 65,000, 60,000, and 51,000. Reaction of polyacrylamide gels with 125 I‐ concanavalin A (Con A) identified two major (apparent M r 180,000 and 130,000) and three minor (apparent M r 230,000, 145,000, and 110,000) Con A‐binding glycoproteins in the PSD fractions. Although some quantitative variation between species and brain regions was apparent, the overall protein and glycoprotein composition was similar for all fractions studied.