By using a eukaryocytic cell expression cloning system, we have isolated cDNAs of the globoside synthase (beta1, 3-N-acetylgalactosaminyltransferase) gene. Mouse fibroblast L cells transfected with SV40 large T antigen and previously cloned Gb3/CD77 synthase cDNAs were co-transfected with a cDNA library prepared from mRNA from human kidney together with Forssman synthase cDNA, and Forssman antigen-positive cells were panned using an anti-Forssman monoclonal antibody. The isolated cDNAs contained a single open reading frame predicting a type II membrane protein with 351 amino acids. Surprisingly, the cDNA clones turned out to be identical with previously reported beta3Gal-T3, which had been cloned by sequence homology with other galactosyltransferases. Substrate specificity analysis with extracts from cDNA-transfected L cells confirmed that the gene product was actually beta1, 3-N-acetylgalactosaminyltransferase that specifically catalyzes the transfer of N-acetylgalactosamine onto globotriaosylceramide. Results of TLC immunostaining of neutral glycolipids from the cDNA-transfected cells also supported the identity of the newly synthesized component as globoside. The results show that glycosyltransferases apparently belonging to a single glycosyltransferase family do not necessarily catalyze reactions utilizing the same acceptor or even the same sugar donor. The globoside synthase gene was expressed in many tissues, such as heart, brain, testis, etc. We propose the designation beta3GalNAc-T1 for the cloned globoside synthase gene.
The chemical reactions and pathways resulting in the formation of oligosaccharides, molecules with between two and (about) 20 monosaccharide residues connected by glycosidic linkages.
A protein modification process that results in the addition of a carbohydrate or carbohydrate derivative unit to a protein amino acid, e.g. the addition of glycan chains to proteins.
IEAUniPathway
Enzymatic activity
This protein acts as an enzyme. It is known to catalyze the following reaction
By using a eukaryocytic cell expression cloning system, we have isolated cDNAs of the globoside synthase (beta1, 3-N-acetylgalactosaminyltransferase) gene. Mouse fibroblast L cells transfected with SV40 large T antigen and previously cloned Gb3/CD77 synthase cDNAs were co-transfected with a cDNA library prepared from mRNA from human kidney together with Forssman synthase cDNA, and Forssman antigen-positive cells were panned using an anti-Forssman monoclonal antibody. The isolated cDNAs contained a single open reading frame predicting a type II membrane protein with 351 amino acids. Surprisingly, the cDNA clones turned out to be identical with previously reported beta3Gal-T3, which had been cloned by sequence homology with other galactosyltransferases. Substrate specificity analysis with extracts from cDNA-transfected L cells confirmed that the gene product was actually beta1, 3-N-acetylgalactosaminyltransferase that specifically catalyzes the transfer of N-acetylgalactosamine onto globotriaosylceramide. Results of TLC immunostaining of neutral glycolipids from the cDNA-transfected cells also supported the identity of the newly synthesized component as globoside. The results show that glycosyltransferases apparently belonging to a single glycosyltransferase family do not necessarily catalyze reactions utilizing the same acceptor or even the same sugar donor. The globoside synthase gene was expressed in many tissues, such as heart, brain, testis, etc. We propose the designation beta3GalNAc-T1 for the cloned globoside synthase gene.
J. Biol. Chem. 273, 12770-12778 (1998)[PubMed:9582303]
BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of a human UDP-galactose:beta-N-acetyl-glucosamine beta-1, 3-galactosyltransferase, designated beta3Gal-T1, revealed no ESTs with identical sequences but a large number with similarity. Three different sets of overlapping ESTs with sequence similarities to beta3Gal-T1 were compiled, and complete coding regions of these genes were obtained. Expression of two of these genes in the Baculo virus system showed that one represented a UDP-galactose:beta-N-acetyl-glucosamine beta-1, 3-galactosyltransferase (beta3Gal-T2) with similar kinetic properties as beta3Gal-T1. Another gene represented a UDP-galactose:beta-N-acetyl-galactosamine beta-1, 3-galactosyltransferase (beta3Gal-T4) involved in GM1/GD1 ganglioside synthesis, and this gene was highly similar to a recently reported rat GD1 synthase (Miyazaki, H., Fukumoto, S., Okada, M., Hasegawa, T., and Furukawa, K. (1997) J. Biol. Chem. 272, 24794-24799). Northern analysis of mRNA from human organs with the four homologous cDNA revealed different expression patterns. beta3Gal-T1 mRNA was expressed in brain, beta3Gal-T2 was expressed in brain and heart, and beta3Gal-T3 and -T4 were more widely expressed. The coding regions for each of the four genes were contained in single exons. beta3Gal-T2, -T3, and -T4 were localized to 1q31, 3q25, and 6p21.3, respectively, by EST mapping. The results demonstrate the existence of a family of homologous beta3-galactosyltransferase genes.
Protein belonging to the set of cell surface antigens found chiefly, but not solely, on blood cells. More than fifteen different blood group systems are recognised in humans. In most cases the antigenic determinant resides in the carbohydrate chains of membrane glycoproteins or glycolipids.
Enzymes that catalyze the transfer of glycosyl (sugar) residues to an acceptor, both during degradation (cosubstrates= water or inorganic phosphate) and during biosynthesis of polysaccharides, glycoproteins and glycolipids. In biosynthetic glycosyl transfers, the common activated monomeric sugar intermediate is a nucleoside diphosphate sugar.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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