Impaired galactosylation of core 2 O-glycans in erythrocytes of beta1,4-galactosyltransferase knockout mice.
O- and N-glycans included in erythrocyte membrane glycoproteins from beta1,4-galactosyltransferase I (GalT-I) knockout mice were analyzed to examine how this enzyme deficiency affects glycosylation of proteins in erythroid cells. The results indicated that greater than 80% of core 2 O-glycans from GalT-I-/- mice are not galactosylated by beta1,4 linkage, resulting in the expression of Neu5Acalpha2 --> 3Galbeta1 --> 3(GlcNAcbeta1 --> 6)GalNAc, while core 2 O-glycans from GalT-I+/+ mice are fully galactosylated and occur as Neu5Acalpha2 --> 3Galbeta1 --> 3(Neu5Acalpha2 --> 3Galbeta1 --> 4GlcNAcbeta1 --> 6)GalNAc. On the other hand, beta1, 4-galactosylation of N-glycans of the mutant was approximately 60% that of the wild type. Thus, it is suggested that GalT-I is predominantly responsible for beta1,4-galactosylation of the core 2 O-glycan branch in erythroid cells.
Kotani
N
N
Department of Biochemistry, University of Tokyo, Tokyo, 108-8639, Japan.
Asano
M
M
Iwakura
Y
Y
Takasaki
S
S
D000818:Animals; D002240:Carbohydrate Sequence; D004912:Erythrocytes / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009237:N-Acetyllactosamine Synthase / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D013997:Time Factors
D008565:Membrane Proteins; D011134:Polysaccharides; D009237:N-Acetyllactosamine Synthase; D005690:Galactose