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Development of Synaptic Glycoproteins: Effect of Postnatal Age on the Synthesis and Concentration of Synaptic Membrane and Synaptic Junctional Fucosyl and Sialyl Glycoproteins
Author(s) -
Fu Sheung Chun,
Cruz Tony F,
Gurd James W
Publication year - 1981
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.1471-4159.1981.tb00571.x
Subject(s) - glycoprotein , fucose , membrane glycoproteins , biochemistry , synapse , chemistry , sialic acid , wheat germ agglutinin , synaptic cleft , neurotransmission , microbiology and biotechnology , biology , lectin , neuroscience , receptor
Synaptic plasma membranes (SPM) and synaptic junctions (SJ) were isolated from the cortices of rats varying in age between 5 and 28 days. Gel electrophoresis of SPM and SJ indicated a marked increase in the concentration of the “PSD protein” (M. W. 52,000) with development. The biosynthesis of glycoproteins was measured following the intracranial injection of [ 3 H]fucose or [ 3 H] N ′‐acetylmannosamine. The incorporation of [ 3 H]fucose into synaptic fractions decreased two‐ to threefold between 10 and 28 days whereas little change in the incorporation of [ 3 H] N ′‐acetylmannosamine occurred over the same period. Gel electrophoretic analyses of labeled synaptic membranes indicated major increases in the relative incorporation of radiolabeled precursors into glycoproteins with apparent molecular weights of 74,000, 65,000, 50,000, and 40,000 with increasing age. Identification of fucosyl and sialyl glycoproteins following reaction with 125 I‐fucose‐binding protein or labeling of sialic acid with NaIO 4 NaB[ 3 H 4 ] demonstrated similar increases in the concentrations of these glycoproteins. Synaptic junctions contained three major glycoproteins with apparent molecular weights of 180,000, 130,000 and 110,000. The reaction of these glycoproteins with 125 I‐fucose‐binding protein increased one‐ to twofold between 10 and 28 days but little variation in their relative distribution or synthesis occurred over this period. The reaction of synaptic junctional glycoproteins GP 180 and GP 110 with 125 I‐wheat germ ag‐glutinin increased between 10 and 28 days. The results indicate that the molecular composition of the synapse continues to evolve after the initial synaptic contact has been formed.