Core fucosylation of high-mannose-type oligosaccharides in GlcNAc transferase I-deficient (Lec1) CHO cells.
During studies on the fucosylation of endogenous proteins in parental (Pro5) and N-acetyl-D-glucosamine (GlcNAc) transferase I-deficient (Lec1) Chinese hamster ovary (CHO) cells, we observed that Lec1 cells incorporate approximately 10-fold less [3H]fucose into macromolecules than Pro5 cells. Interestingly, most of the labelled oligosaccharides from both cell types could be released from the macromolecules by digestion with peptide N-glycosidase F (PNGase F). This was unexpected for Lec1 cells because they do not synthesize complex- or hybrid-type N-glycans. Structural analyses of the fucosylated oligosaccharides from Lec1 cells showed the fucose to be in an alpha 1,6 linkage to the core GlcNAc of relatively small oligomannose N-glycans (Man4GlcNAc2 and Man5GlcNAc2, where Man is D-mannose). Comparing the sizes of oligomannose N-glycans from Pro5 and Lec1 cells demonstrated a much higher proportion of the small (Man4GlcNAc2 and Man5GlcNAc2) oligomannose species in Lec1 cells. These results suggest that the core alpha 1,6 fucosyltransferase will fucosylate small (Man4-Man5GlcNAc2), but not large (Man8-Man9GlcNAc2) oligomannose N-glycans.
Lin
A I
AI
Department of Biochemistry and Cell Biology, SUNY-Stony Brook 11794-5215, USA.
Philipsberg
G A
GA
Haltiwanger
R S
RS
D000818:Animals; D016466:CHO Cells; D002240:Carbohydrate Sequence; D006224:Cricetinae; D005643:Fucose / Q000737:chemistry / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism; D008358:Mannose / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000172:deficiency*; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism
D006023:Glycoproteins; D009844:Oligosaccharides; D011134:Polysaccharides; D005643:Fucose; D017351:N-Acetylglucosaminyltransferases; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase; D008358:Mannose