β3-Galactosyltransferase-IV (GM1 Synthase)
β3-Galactosyltransferase-IV (β3GalT-IV) is an enzyme which catalyzes the conversion of GM2, GD2, and asialo-GM2 to GM1, GD1b, and asialo-GM1 (Gal), respectively (Miyazaki et al. 1997). This step is critical for the synthesis of major complex gangliosides such as GM1, GD1a, GDlb, GT1b, and GQ1b, which are enriched in the nervous system of vertebrates. Therefore, all major complex gangliosides are synthesized via the direct products of this enzyme. The cDNAs of β3GalT-IV were isolated by a eukaryocyte expression cloning system in 1997 (Miyazaki et al. 1997). This enzyme utilizes only glycolipid acceptors, not glycoproteins, and no other enzymes (genes) catalyzing similar functions have been detected to date. In the mouse genome (Mus musculus major histocompatibility locus class II region), a highly homologous gene as an orthologue to rat β3-galactosyltransferase-IV was reported by Rowen et al. (see AF100956, AF110520).
KeywordsCholera Toxin Neural Retina Complex Ganglioside High mRNA Expression Level Substrate Specificity Enzyme
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- Amado M, Almeida R, Carneiro F, Levery SB, Holmes EH, Nomoto M, Hollingsworth MA, Hassan H, Schwientek T, Nielsen PA, Bennett EP, Clausen H (1998) A family of human β3-galactosyltransferases. Characterization of four members of a UDP-galactose:β-N-acetyl-glucosamine/beta-nacetyl-galactosamine β-1,3-galactosyltransferase family. J Biol Chem 273:12770–12778PubMedCrossRefGoogle Scholar