Biosynthesis of lipid-linked oligosaccharides in embryonic liver. Formation of mannose containing derivatives

Abstract

1. 1. In the presence of exogenous dolichyl phosphate mannosyl transferase activity towards dolichyl phosphate was nearly 3-fold higher in microsomes from pig embryonic liver compared to that from adult liver. 2. 2. After incubation of microsomes from embryonic liver with UDP- N-acetylglucosamine and GDP-[ 14C]mannose lipid-linked tri- to undecasaccharides were discovered in CHCl 3-CH 3OH (2:1, v/v) and CHCl 3-CH 3OH-H 2O (1:1:0.3, by vol) extracts. The main proportion of the radioactivity was incorporated into penta-, sexta and undecasaccharides. 3. 3. Amphomycin at concentration 500 μg/ml inhibited almost completely dolichyl phosphate mannose synthesis in embryonic liver microsomes without inhibition the formation of lipid-linked penta- and sextasaccharides. 4. 4. It was suggested that mannose transferred to lipid-linked tetra- to heptasaccharides comes from GDP-mannose but not from dolichyl phosphate mannose.