Gangliosides and sialosylglycoproteins in coated vesicles from bovine brain.
The content of gangliosides and sialosylglycoproteins was investigated in a coated-vesicle-enriched fraction prepared from bovine brain by the method of Pearse [(1975) J. Mol. Biol. 97, 93-98] and further purified by g.p.c. (glass-permeation chromatography) [Pfeffer & Kelly (1981) J. Cell Biol. 91, 385-391]. From morphological criteria and from the analysis of the polypeptide pattern on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis the coated-vesicle fraction (CV-fraction) appeared more than 95% pure. The ganglioside-NeuAc (N-acetylneuraminate), glycoprotein-NeuAc, phospholipid and cholesterol contents of CV-fraction were compared with those of bovine brain synaptic plasma membranes (SPM). The cholesterol to phospholipid molar ratio was 0.47 +/- 0.07 in CV-fraction and 1.06 +/- 0.08 in SPM. The ganglioside-NeuAc and glycoprotein-NeuAc to phospholipid molar ratios were 0.047 and 0.020 respectively in CV-fraction and 0.039 and 0.016 respectively in SPM. The (Na+ + K+)-dependent ATPase activity sensitive to ouabain (in mumol of Pi/h per nmol of phospholipid) was 1.04 in CV-fraction and 0.63 in SPM; the ratio between this activity and the activity resistant to ouabain was 2 in CV-fraction and 1.4 in SPM. A t.l.c. analysis of the ganglioside fractions showed that most of the ganglioside species present in SPM were present in CV-fraction. In a rat brain coated-vesicle preparation not subjected to g.p.c., the activities [as sugar-radioactivity (c.p.m.) transferred/h per mumol of phospholipid] of the enzymes CMP-NeuAc:sialosyl-lactosylceramide (GM3) sialosyl-, UDP-Gal:N-acetylgalactosaminyl(sialosyl)lactosylceramide (GM2) galactosyl- and UDP-GalNAc:sialosyl-lactosylceramide (GM3) N-acetylgalactosaminyl-transferases, which were considered Golgi-apparatus markers, were about 19, 16 and 10% respectively of those determined in rat brain neuronal perikaryon-enriched fractions. Taken together, the results indicate that most of the major gangliosides are constituents of coated vesicles.
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D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D011992:Endosomes / Q000378:metabolism*; D005732:Gangliosides / Q000378:metabolism*; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism
D005732:Gangliosides; D009419:Nerve Tissue Proteins; D012795:Sialoglycoproteins; D014166:Transferases; D000251:Adenosine Triphosphatases