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Lipid carriers in the synthesis of high-mannose glycoproteins in algae

1979; Elsevier BV; Volume: 586; Issue: 3 Linguagem: Inglês

10.1016/0304-4165(79)90045-x

1872-8006

Pedro Romero, H. Esteban Hopp, Rafael Pont‐Lezica,

Glycosylation and Glycoproteins Research

Particulate preparations from the chlorophyta Prototheca zopfii catalyze the incorporation of mannose and N-acetylglucosamine into glycolipids. These had been characterized as lipid monophosphate mannose, lipid pyrophosphate N,N'-diacetylchitobiose and various lipid-linked oligosaccharides containing two N-acetylglucosamine residues plus a variable number of mannose residues. The lipid moiety has the properties expected for dolichyl phosphate. The oligosacchride-linked lipids serve as precursors for the formation of a polymer sensible to pronase digestion. The oligosaccharide is linked by N-glycosidic linkage to an asparagine residue. In longer incubation periods, a polymer insensitive to pronase hydrolysis, but precipitable by copper salts such as cell wall mannans is formed. Polymer formation is inhibited by 1 mM bacitracin. The reactions leading to the formation of the mannoprotein were found associated to the rough endoplasmic reticulum. The synthesis of mannans was found to occur in the Golgi vesicles.