Biosynthesis of glycoproteins inCandida albicans: Processing of a Man6-GlcNAc2-Asn oligosaccharide by membrane fractions

Abstract
When a M6-GlcNAc2-Asn oligosaccharide isolated from ovalbumin was incubated with a membrane fraction from Candida albicans and GDP-[14C]Man only one set of low molecular mass products was obtained, which contained 7, 8, 9 and 10 mannose residues in a ratio of 13:6:3:1, as deduced from fast atomic bombardment mass spectrometry analysis. When a mixture of these products was reincubated with a fresh membrane preparation and cold GDP-Man, no further mannose incorporation was observed, indicating that these compounds are not recognized as substrates by the glycan processing system in this organism. Results are discussed in terms of the early glycan processing steps in C. albicans.