Handbook of Glycosyltransferases and Related Genes pp 1273-1282 | Cite as
Mannosyl-Oligosaccharide Glucosidase (Glucosidase I, MOGS)
The synthesis of asparagine-linked glycoproteins in eukaryotes occurs via the transfer of dolichol-linked Glc3Man9GlcNAc2 oligosaccharide at specific Asn-X-Ser/Thr sequons via the oligosaccharyl transferase (Kornfeld and Kornfeld 1985; Waechter and Lennarz 1976). Following transfer of this oligosaccharide to the peptide, sugar residues are removed or added by specific enzymes to create a diverse population of high-mannose, hybrid, or complex-type glycans as the glycoprotein moves through the secretory pathway. The first step in the remodeling of the Glc3Man9GlcNAc2 oligosaccharide is the removal of a single α1,2-linked glucose from the nonreducing terminal end of the α1,3Man branch to produce Glc2Man9GlcNAc2 (Fig. 113.1). This initial processing step is completed by mannosyl-oligosaccharide glucosidase (MOGS), also known as α-glucosidase I, which is a member of CAZy glycosyl hydrolase family 63 (Henrissat 1991). The removal of the terminal α1,2-linked glucose in the endoplasmic reticulum is the initial step in the processing and potential remodeling of N-glycans in the secretory pathway. Following removal of the distal α1,2 glucose residue to produce Glc2Man9GlcNAc2, a second ER α-glucosidase, the hetero-dimeric α-glucosidase II, removes the two remaining glucose residues.
KeywordsBovine Mammary Gland Putative Binding Motif Chinese Hamster Ovary Mutant Oligosaccharyl Transferase Initial Processing Step
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