N-linked oligosaccharide processing is not necessary for glycoprotein secretion in plants.
The role of N-glycans in the secretion of glycoproteins by suspension-cultured sycamore cells was studied. The transport of glycoproteins to the extracellular compartment was investigated in the presence of a glycan-processing inhibitor, castanospermine. Castanospermine has been selected because it inhibits homogeneously glycan maturation in sycamore cells and leads to the accumulation of a single immature N-glycan. The structure of this glycan has been identified as Glc3Man7GlcNAc2 by labeling experiments, affinity chromatography on concanavalin A-Sepharose and proton NMR. In contrast with previous results showing that N-glycosylation is a prerequisite for secretion of N-linked glycoproteins, this secretion is not affected by the presence of castanospermine. As a consequence, the presence of this unprocessed glycan is sufficient for an efficient secretion of glycoproteins in the extracellular compartment of suspension-cultured sycamore cells.
Lerouge
P
P
Centre Régional Universitaire de Spectroscopie, CNRS-URA 464, Mont Saint Aignan, France.
Fichette-Lainé
A C
AC
Chekkafi
A
A
Avidgor
V
V
Faye
L
L
D002240:Carbohydrate Sequence; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006023:Glycoproteins / Q000378:metabolism*; D007212:Indolizines / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017421:Sequence Analysis; D014197:Trees / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D054836:Indolizidines
D004791:Enzyme Inhibitors; D006023:Glycoproteins; D007212:Indolizines; D009844:Oligosaccharides; D010940:Plant Proteins; C037806:castanospermine; D054836:Indolizidines