Open AccessCharacterization of Crithidia fasciculata oligosaccharide‐lipid and its elongation by bovine mammary microsomes
Author(s) -
KATIAL Albine,
PRAKASH Chandra,
VIJAY Inder K.
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08223.x
Subject(s) - crithidia fasciculata , biochemistry , biosynthesis , glycoprotein , glycolipid , mannose , oligosaccharide , microsome , glycosylation , chemistry , lipid metabolism , biology , enzyme
It was recently shown that a Man 7 (GlcNAc) 2 ‐lipid species serves as the precursor for the biosynthesis of asparagine‐linked glycoproteins in the trypanosomatid Crithidia fasciculata . Preliminary results indicated it to be similar to the intermediate in the major pathway for the biosynthesis of lipid‐linked Glc 3 Man 9 (GlcNAc) 2 in animal systems. To explore the potential of this glycolipid as an acceptor for studying the biosynthesis of mammary glycoproteins, we conducted a detailed structural analysis of the labelled Man 7 (GlcNAc) 2 ‐lipid isolated from exponentially growing cells of C. fasciculata . The results showed its structure to be Manα1 → 2Manα1 → 2Manα1 → 3(Manα1 → 2Manα1 → 3Manα1 → 6)Manβ→ GlcNAcβ→ GlcNAc, identical to the nonasaccharide synthesized by the animal systems. Incubation of the Man 7 (GlcNAc) 2 ‐lipid with bovine mammary microsomes along with GDP‐mannose or mannosyl‐phosphodolichol elongates it to give Man 9 (GlcNAc) 2 ‐lipid having the same structure as the corresponding intermediate in animal systems. Inhibition of the elongation reaction by EDTA or amphomycin indicates that the intermediary formation of mannosyl‐phosphodolichol is required for the incorporation of mannose residues into the nonasaccharide‐lipid. Mannosyl phosphoretinol failed to serve as a mannosyl donor in this reaction.