Biosynthesis of blood group I antigens. Identification of a UDP-GlcNAc:GlcNAc beta 1-3Gal(-R) beta 1-6(GlcNAc to Gal) N-acetylglucosaminyltransferase in hog gastric mucosa

A beta 1-6N-acetylglucosaminyltransferase has been identified in microsomal preparations from hog gastric mucosa which is able to synthesize branch points in branched lactosaminoglycans (blood group I antigenic structures). The enzyme can be assayed specifically using the synthetic trisaccharide Glc...

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Bibliographic Details
Published in:The Journal of biological chemistry 1984-11, Vol.259 (21), p.13385-13390
Main Authors: Piller, F, Cartron, J P, Maranduba, A, Veyrières, A, Leroy, Y, Fournet, B
Format: Article
Language:English
Subjects:
Animals
Blood Group Antigens
Carbohydrate Conformation
Carbohydrate Sequence
Gastric Mucosa - enzymology
Hemagglutination Inhibition Tests
I Blood-Group System
Kinetics
Mass Spectrometry
Microsomes - enzymology
Substrate Specificity
Swine
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Summary:A beta 1-6N-acetylglucosaminyltransferase has been identified in microsomal preparations from hog gastric mucosa which is able to synthesize branch points in branched lactosaminoglycans (blood group I antigenic structures). The enzyme can be assayed specifically using the synthetic trisaccharide GlcNAc beta 1-3Gal beta 1-4Glc beta-OMe as acceptor. The product of the transferase reaction was isolated and identified by methylation analysis as, (Formula: see text) Into this tetrasaccharide two galactose residues were incorporated by the specific beta-N-acetylglucosaminide beta 1-4-galactosyltransferase from bovine milk. Thus a hexasaccharide was formed which was shown to inhibit strongly a murine monoclonal and a human anti-I antibody. Using a variety of oligosaccharides and glycolipids, which correspond to structures found in linear lactosaminoglycan chains, the acceptor substrate specificity of the branching enzyme was determined. From these results it is concluded that branching occurs only during the elongation process at the nonreducing end and follows a well-defined order. N-Acetylglucosamine is first transferred to position 3 of a terminal galactose followed immediately by the addition of a second N-acetylglucosamine to position 6; only then the 1-3 and the 1-6 branches are further elongated by galactose residues.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)90706-4