Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cDNA encoding a novel galactosyltransferase was identified based on BLAST analysis of expressed sequence tags, and the cDNA clones were isolated from a human melanoma line library. The new cDNA sequence encoded a type II membrane protein with 327 amino acid sequence and showed 38% homology to the Caenorhabditis elegans sqv-3 gene involved in the vulval invagination and oocyte development. Extracts from L cells transfected with the galactosyltransferase cDNA in an expression vector and a fusion protein with protein A exhibited marked galactosyltransferase activity specific for p-nitrophenyl-beta-D-xylopyranoside. Moreover, transfection with the cloned cDNA restored glycosaminoglycan synthesis of galactosyltransferase I-deficient Chinese hamster ovary mutant pgsB-761 cells. Analysis of the enzyme product by beta-galactosidase digestion, mass spectroscopy, and NMR spectroscopy revealed that the reaction product was formed via beta-1,4 linkage, indicating that the enzyme is galactosyltransferase I (UDP-galactose:O-beta-D-xylosylprotein 4-beta-D-galactosyltransferase, EC 2.4.1.133) involved in the synthesis of the glycosaminoglycan-protein linkage region of proteoglycans.
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PMID:Human homolog of Caenorhabditis elegans sqv-3 gene is galactosyltransferase I involved in the biosynthesis of the glycosaminoglycan-protein linkage region of proteoglycans. 1043 55

The alpha1,2-mannosidase Mns1p involved in the N-glycosidic pathway in Saccharomyces cerevisiae is a type II membrane protein of the endoplasmic reticulum. The localization of Mns1p depends on retrieval from the Golgi through a mechanism that involves Rer1p. A chimera consisting of the transmembrane domain of Mns1p fused to the catalytic domain of the Golgi alpha1,2-mannosyltransferase Kre2p was localized in the endoplasmic reticulum of Deltapep4 cells and in the vacuoles of rer1/Deltapep4 by indirect immunofluorescence. The split-ubiquitin system was used to determine if there is an interaction between Mns1p and Rer1p in vivo. Co-expression of NubG-Mns1p and Rer1p-Cub-protein A-lexA-VP16 in L40 yeast cells resulted in cleavage of the reporter molecule, protein A-lexA-VP16, detected by western blot analysis and by expression of beta-galactosidase activity. Sec12p, another endoplasmic reticulum protein that depends on Rer1p for its localization, also interacted with Rer1p using the split-ubiquitin assay, whereas the endoplasmic reticulum protein Ost1p showed no interaction. A weak interaction was observed between Alg5p and Rer1p. These results demonstrate that the transmembrane domain of Mns1p is sufficient for Rer1p-dependent endoplasmic reticulum localization and that Mns1p and Rer1p interact. Furthermore, the split-ubiquitin system demonstrates that the C-terminal of Rer1p is in the cytosol.
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PMID:Interaction of the endoplasmic reticulum alpha 1,2-mannosidase Mns1p with Rer1p using the split-ubiquitin system. 1179 27

In the yeast Saccharomyces cerevisiae, the expression of phospholipid biosynthetic genes, including the INO1 gene (encoding inositol-1-phosphate synthase), is coordinately regulated by a cis-acting transcriptional element, UAS(INO) (inositol-sensitive upstream activating sequence). For this paper we studied the effect of SCS2 disruption on INO1 expression. SCS2 encodes a type II membrane protein and its deletion leads to inositol auxotrophy at temperatures above 34 degrees C. We found that the expression of the INO1 gene was reduced in the scs2Delta strain even when the cells were cultured under derepressing conditions for INO1 expression. However, the beta-galactosidase gene fused with the INO1 promoter region was expressed normally in the scs2Delta strain. The phospholipid composition of scs2Delta cells was not dramatically changed compared with wild-type cells at 28 degrees C, but the phosphatidylinositol level was reduced in scs2Delta cells cultured at 34 degrees C. In addition, elevated phosphatidylcholine synthesis through the CDP-choline pathway was observed in the scs2Delta strain, and the disruption of genes involved in the CDP-choline pathway rescued the INO1 expression defect of the scs2Delta strain. These results indicate that Scs2p can contribute to coordinated phospholipid metabolism including INO1 expression by regulating phosphatidylcholine synthesis through the CDP-choline pathway.
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PMID:Role of the yeast VAP homolog, Scs2p, in INO1 expression and phospholipid metabolism. 1276

We found, using a BLAST search, a novel human gene (GenBank trade mark accession number BC029564) that possesses beta3-glycosyltransferase motifs. The full-length open reading frame consists of 500 amino acids and encodes a typical type II membrane protein. This enzyme has a domain containing beta1,3-glycosyltransferase motifs, which are widely conserved in the beta1,3-galactosyltransferase and beta1,3-N-acetylglucosaminyltransferase families. The putative catalytic domain was expressed in human embryonic kidney 293T cells as a soluble protein. Its N-acetylgalactosaminyltransferase activity was observed when N-acetylglucosamine (GlcNAc) beta1-O-benzyl was used as an acceptor substrate. The enzyme product was determined to have a beta1,3-linkage by NMR spectroscopic analysis, and was therefore named beta1,3-N-acetylgalactosaminyltransferase-II (beta3GalNAc-T2). The acceptor substrate specificity of beta3GalNAc-T2 was examined using various oligosaccharide substrates. Galbeta1-3(GlcNAcbeta1-6)GalNAcalpha1-O-para-nitrophenyl (core 2-pNP) was the best acceptor substrate for beta3GalNAc-T2, followed by GlcNAcbeta1-4GlcNAcbeta1-O-benzyl, and GlcNAcbeta1-6GalNAcalpha1-O-para-nitrophenyl (core 6-pNP), among the tested oligosaccharide substrates. Quantitative real time PCR analysis revealed that the beta3Gal-NAc-T2 transcripts was restricted in its distribution mainly to the testis, adipose tissue, skeletal muscle, and ovary. Its putative orthologous gene, mbeta3GalNAc-T2, was also found in a data base of mouse expressed sequence tags. In situ hybridization analysis with mouse testis showed that the transcripts are expressed in germ line cells. beta3GalNAc-T2 efficiently transferred GalNAc to N-glycans of fetal calf fetuin, which was treated with neuraminidase and beta-galactosidase. However, it showed no activity toward any glycolipid examined. Although the GalNAcbeta1-3GlcNAcbeta1-R structure has not been reported in humans or other mammals, we have discovered a novel human glycosyltransferase producing this structure on N- and O-glycans.
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PMID:A novel human beta1,3-N-acetylgalactosaminyltransferase that synthesizes a unique carbohydrate structure, GalNAcbeta1-3GlcNAc. 1472 82