title: Biosynthesis of mammary glycoproteins. Partial characterization of the sequence for the assembly of lipid-linked saccharides.
abstract: Incubation of a membrane preparation from the lactating bovine mammary gland with UDP-[3H]GlcNAc, GDP-[14C]Man, and UDP-[3H]Glc results in the biosynthesis of 15 lipid-linked saccharides that differ from one another by a monosaccharide unit. Pulse and chase kinetics indicate that these glycolipids are related to one another as precursor products for the biosynthesis of asparagine-linked glycoproteins of this tissue. [Man-14C]- and [Man-14C, GlcNAc-3H]saccharides were prepared from corresponding glycolipids by mild acid hydrolysis. Following extensive purification by paper and gel filtration chromatography, structural characterization was conducted on tri-, tetra-, penta-, and undecasaccharides via size determination on calibrated columns of Bio-Gel P-2 and P-4, compositional analysis, exo- and endoglycosidase digestions, methylation, Smith degradation, and acetolysis. These structures were identified as: Man beta 1 leads to 4(3)GlcNAc beta 1 leads to 4(3)Glc-NAc, Man alpha 1 leads to 3Man beta 1 leads to 4(3)GlcNAc beta 1 leads to 4(3)GlcNAc, Man alpha 1 leads to 3(Man alpha 1 leads to 6)Man beta 1 leads to 4(3)Glc NAc beta 1 leads to 4(3)Glc-NAc, and Man alpha 1 leads to 2 Man alpha 1 leads to 2Man alpha 1 leads to 3(Man alpha 1 leads to 2Man alpha 1 leads to 6[Man alpha 1 leads to 2Man alpha 1 leads to 3]Man alpha 1 leads to 6)Man beta 1 leads to 4(3)GlcNAc beta 1 leads to 4(3)GlcNAc.
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002250:Carbon Radioisotopes; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006017:Glycolipids / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis*; D006155:Guanosine Diphosphate Mannose / Q000378:metabolism; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D011247:Pregnancy; D014316:Tritium; D014532:Uridine Diphosphate Glucose / Q000378:metabolism; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D006017:Glycolipids; D006023:Glycoproteins; D014316:Tritium; D006155:Guanosine Diphosphate Mannose; D014537:Uridine Diphosphate N-Acetylglucosamine; D014532:Uridine Diphosphate Glucose