α4-N-Acetylglucosaminyltransferase (α4GnT) is a glycosyltransferase that mediates transfer of GlcNAc with α1,4-linkage from UDP-GlcNAc to βGal residues preferentially present in O-glycans, forming GlcNAcα1-4Galβ-R (Nakayama et al. 1999). In the human, glycoproteins having GlcNAcα1-4Galβ-R at nonreducing terminals are exclusively limited to the mucins secreted from gland mucous cells (cardiac gland cell, mucous neck cell, pyloric gland cell) of the stomach, Brunner’s glands of the duodenum, accessory glands of the pancreaticobiliary tract, and pancreatic ducts showing gastric metaplasia (Nakamura et al. 1998) (Fig. 1). Thus, these mucous glycoproteins as a whole have been regarded as gastric gland mucous cell-type mucin, and α4GnT plays a key role in synthesizing this particular mucin which has GlcNAcα1-4Galβ-R structures. In the gastric mucin, the oligosaccharides having GlcNacα1-4Galβ-R structures were found to be attached to not only MUC6 but also MUC5AC (Zhang et al. 2001).
KeywordsGastric Mucin Mucous Glycoprotein Mucous Neck Cell Nonreducing Terminal Gastric Metaplasia
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