The organization of carbohydrate in mouse synaptosomal plasma membrane.
Analysis of synaptosomal plasma membrane from mouse brain by SDS gel electrophoresis reveals a large number of glycoprotein and glycolipid species, as distinguished by periodic acid Schiff or by the distribution of in vivo incorporated 3H-fucose label. The topographical distribution of this carbohydrate in the plasma membrane was examined by labelling intact synaptosomes and isolated membrane with galactose oxidase (E.C. 1.1.2.9.)-3H-NaBH4. In both, gangliosides and a wide spectrum of glycoprotein species were labelled. Extraction of SPM with 0.05 N NaOH at 0 degrees C removed about two-thirds of the membrane's protein. Gel electrophoresis of the solubilized material revealed partial or complete extraction of a large number of polypeptide species; however, all of the glycoproteins, as well as the  glycolipid, remained in the insoluble pellet. These results indicate a highly asymmetric arrangement of glycoproteins and glycolipids in SPM; most or all of these species reside on the external surface of the synaptosome, accessible to galactose oxidase. The glycoproteins appear to be more deeply-buried in the lipid bilayer than the other polypeptide species, as has been found in other systems.
D000818:Animals; D001894:Borohydrides; D002241:Carbohydrates / Q000032:analysis*; D002462:Cell Membrane / Q000032:analysis* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D005692:Galactose Oxidase; D006023:Glycoproteins / Q000378:metabolism; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000032:analysis; D051379:Mice; D013574:Synaptosomes / Q000032:analysis* / Q000648:ultrastructure
D001894:Borohydrides; D002241:Carbohydrates; D006023:Glycoproteins; D008563:Membrane Lipids; D005692:Galactose Oxidase