Glycoproteins secreted from suspension-cultured tobacco BY2 cells have distinct glycan structures from intracellular glycoproteins.
Glycan structures of glycoproteins secreted in the spent medium of tobacco BY2 suspension-cultured cells were analyzed. The N-glycans were liberated by hydrazinolysis and the resulting oligosaccharides were labeled with 2-aminopyridine. The pyridylaminated (PA) glycans were purified by reversed-phase and size-fractionation HPLC. The structures of the PA sugar chains were identified by a combination of the two-dimensional PA sugar chain mapping, MS analysis, and exoglycosidase digestion. The ratio (40:60) of the amount of glycans with high-mannose-type structure to that with plant-complex-type structure of extracellular glycoproteins is significantly different from that (ratio 10:90) previously found in intracellular glycoproteins [Palacpac et al., Biosci. Biotechnol. Biochem. 63 (1999) 35-39]. Extracellular glycoproteins have six distinct N-glycans (marked by *) from intracellular glycoproteins, and the high-mannose-type structures account for nearly 40% (Man5GlcNAc2, 28.8%; Man6GlcNAc2*, 6.4%; and Man7GlcNAc2*, 3.8%), while the plant-complex-type structures account for nearly 60% (GlcNAc2Man3Xyl1GlcNAc2*, 32.1%; GlcNAc1Man3Xyl1GlcNAc2 (containing two isomers)*, 6.2%; GlcNAc2Man3GlcNAc2*, 4.9%; Man3Xyl1Fuc1GlcNAc2, 8.3%; and Man3Xyl1GlcNAc2, 3.7%).
Misaki
R
R
The International Center for Biotechnology, Osaka University, Suita-shi, Japan.
Kimura
Y
Y
Fujiyama
K
K
Seki
T
T
D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry; D014026:Nicotiana / Q000737:chemistry*
D006023:Glycoproteins; D010940:Plant Proteins; D011134:Polysaccharides