Molecular cloning of a human UDP-galactose:GlcNAcbeta1,3GalNAc beta1, 3 galactosyltransferase gene encoding an O-linked core3-elongation enzyme.
Using the full-length amino-acid sequences of the human beta1,3 galactosyltransferase (beta3GalT)-I, -II and III enzymes as query, we have identified an additional member of the beta3GalT gene family within a sequenced region of the human chromosome 21 as found in GenBank. The novel human beta3GalT-V gene included an open reading frame of 933 bp encoding a protein of 310 amino acids with a short N-terminal cytoplasmic tail, a single predicted transmembrane domain and a large lumenal catalytic domain. The human beta3GalT-V protein showed 34%, 27%, 31% and 23% sequence identity with the human beta3GalT-I, -II, -III and -IV enzymes, respectively. The expression of beta3GalT-V as a recombinant protein in Sf9 insect cells confirmed the galactosyltransferase activity catalyzed by this enzyme. Similarly to beta3GalT-I, -II and -III, the beta3GalT-V enzyme used beta-linked GlcNAc as an acceptor, but unlike the former enzymes beta3GalT-V exhibited a marked preference for the O-linked core3 GlcNAcbeta1,3GalNAc substrate. The beta3GalT-V gene was mainly expressed in human small intestine and to a lesser extent in pancreas and testis. Although beta3GalT-V transcripts were not detected in normal colon tissue, based on Northern analysis, beta3GalT-V mRNA was found in the adenocarcinoma cell line Colo 205.
Zhou
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Institute of Physiology, University of Zürich, Switzerland.
Berger
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EG
Hennet
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D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured; D000519:alpha-Galactosidase / Q000494:pharmacology; D001616:beta-Galactosidase / Q000494:pharmacology
D005700:Galactosyltransferases; C120745:UDP-galactose N-acetylglucosaminyl-1-3-N-acetylgalactosamine beta-1,3-galactosyltransferase; D000519:alpha-Galactosidase; D001616:beta-Galactosidase