Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara
Electronic Gene Ontology annotations created by ARBA machine learning models
Falcon deep research report for human A4GNT
Expression cloning of a human alpha1, 4-N-acetylglucosaminyltransferase that forms GlcNAcalpha1-->4Galbeta-->R, a glycan specifically expressed in the gastric gland mucous cell-type mucin.
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Human A4GNT transfers alpha-1,4-linked GlcNAc to terminal beta-galactose, with core-2-branched mucin O-glycans the most efficient tested acceptors.
"An in vitro GlcNAc transferase assay by using a soluble alpha4GnT revealed that alpha1,4-linked GlcNAc residues are transferred most efficiently to core 2 branched O-glycans"
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Expression of A4GNT in gastric adenocarcinoma cells was sufficient to generate class III mucin reactivity.
"Transfection of alpha4GnT cDNA into gastric adenocarcinoma AGS cells produced class III mucin, indicating that alpha4GnT is responsible for the formation of class III Con A reactivity."
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The cloned 340-residue product has the predicted topology of a type-II membrane protein.
"The deduced amino acid sequence predicts a type II membrane protein with 340 amino acids, showing no significant similarity with any other proteins."
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Core-2 O-glycans are preferred over core-1 acceptors, while core-3 activity was barely detectable in the tested panel.
"The α4GnT was found to act more efficiently on core 2 branched O -glycans and less efficiently on core 1 oligosaccharide. However, this enzyme hardly transferred GlcNAc to core 3 oligosaccharide, GlcNAcβ1→3GalNAcα→ p NP (Fig. 5 )."
Immunohistochemical demonstration of alpha1,4-N-acetylglucosaminyltransferase that forms GlcNAcalpha1,4Galbeta residues in human gastrointestinal mucosa.
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Endogenous human A4GNT was localized largely to the Golgi region of glandular mucous cells producing its terminal glycan product.
"Expression of alpha4GnT was largely associated with the Golgi region of mucous cells that produce the mucous glycoproteins having GlcNAcalpha1-->4Galbeta-->R, such as the glandular mucous cells of stomach and Brunner's gland."
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Human gastric MUC5AC and MUC6 carry the GlcNAc-alpha-1,4-Gal-beta-R structure generated by A4GNT.
"An immunoprecipitation experiment disclosed that two distinct mucin proteins, MUC5AC and MUC6 present in gastric mucin, carried the GlcNAcalpha1-->4Galbeta-->R structures."
Natural antibiotic function of a human gastric mucin against Helicobacter pylori infection.
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Terminal alpha-1,4-linked GlcNAc O-glycans in human gastric mucin inhibit H. pylori growth by blocking synthesis of a bacterial cell-wall sterol glycoside.
"Here, we report that these O-glycans have antimicrobial activity against H. pylori, inhibiting its biosynthesis of cholesteryl-alpha-D-glucopyranoside, a major cell wall component."
Essential role of gastric gland mucin in preventing gastric cancer in mice.
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A4gnt-null mice lacked gastric alpha-GlcNAc and all developed gastric adenocarcinoma through a hyperplasia-dysplasia-carcinoma sequence without H. pylori infection.
"A4gnt(-/-) mice showed complete lack of αGlcNAc expression in gastric gland mucin. Surprisingly, all the mutant mice developed gastric adenocarcinoma through a hyperplasia-dysplasia-carcinoma sequence in the absence of H. pylori infection."
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Loss of the terminal glycan activated inflammatory and growth-factor programs in gastric mucosa, supporting a protective role in mucosal homeostasis.
"Microarray and quantitative RT-PCR analysis revealed upregulation of genes encoding inflammatory chemokine ligands, proinflammatory cytokines, and growth factors, such as Ccl2, Il-11, and Hgf in the gastric mucosa of A4gnt(-/-) mice."
A4GNT transfers GlcNAc to core 2 mucins
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Reactome represents the human A4GNT reaction as alpha-1,4-linked GlcNAc transfer to beta-galactose on core-2-branched mucins.
"Alpha-1,4-N-acetylglucosaminyltransferase (A4GNT) can catalyse the transfer of N-acetylglucosamine (GlcNAc) to core 2 branched mucins, creating an alpha1,4-linkage with beta-Gal residues"
O-linked glycosylation of mucins