Beta-1,4-galactosyltransferase 1 is an enzyme that in humans is encoded by the B4GALT1 gene. [4] [5]
This gene is one of seven beta-1,4-galactosyltransferase (beta4GalT) genes. They encode type II membrane-bound glycoproteins that appear to have exclusive specificity for the donor substrate UDP-galactose; all transfer galactose in a beta1,4 linkage to similar acceptor sugars: GlcNAc, Glc, and Xyl. Each beta4GalT has a distinct function in the biosynthesis of different glycoconjugates and saccharide structures. As type II membrane proteins, they have an N-terminal hydrophobic signal sequence that directs the protein to the Golgi apparatus and which then remains uncleaved to function as a transmembrane anchor. By sequence similarity, the beta4GalTs form four groups: beta4GalT1 and beta4GalT2, beta4GalT3 and beta4GalT4, beta4GalT5 and beta4GalT6, and beta4GalT7. This gene is unique among the beta4GalT genes because it encodes an enzyme that participates both in glycoconjugate and lactose biosynthesis. For the first activity, the enzyme adds galactose to N-acetylglucosamine residues that are either monosaccharides or the nonreducing ends of glycoprotein carbohydrate chains. The second activity is restricted to lactating mammary tissues where the enzyme forms a heterodimer with alpha-lactalbumin to catalyze UDP-galactose + D-glucose <=> UDP + lactose. The two enzymatic forms result from alternate transcription initiation sites and post-translational processing. Two transcripts, which differ only at the 5' end, with approximate lengths of 4.1 kb and 3.9 kb encode the same protein. The longer transcript encodes the type II membrane-bound, trans-Golgi resident protein involved in glycoconjugate biosynthesis. The shorter transcript encodes a protein which is cleaved to form the soluble lactose synthase. [5]
Galactosyltransferase is a type of glycosyltransferase which catalyzes the transfer of galactose. An example is B-N-acetylglucosaminyl-glycopeptide b-1,4-galactosyltransferase.
In enzymology, a glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase is an enzyme that catalyzes the chemical reaction
UDP-GalNAc:beta-1,3-N-acetylgalactosaminyltransferase 1 is an enzyme that in humans is encoded by the B3GALNT1 gene.
CMP-sialic acid transporter is a protein that in humans is encoded by the SLC35A1 gene.
UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 2 is an enzyme that in humans is encoded by the B3GNT2 gene.
ST3 beta-galactoside alpha-2,3-sialyltransferase 3, also known as ST3GAL3, is a protein which in humans is encoded by the ST3GAL3 gene.
Beta-1,4-galactosyltransferase 7 also known as galactosyltransferase I is an enzyme that in humans is encoded by the B4GALT7 gene. Galactosyltransferase I catalyzes the synthesis of the glycosaminoglycan-protein linkage in proteoglycans. Proteoglycans in turn are structural components of the extracellular matrix that is found between cells in connective tissues.
Alpha-1,3-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase is an enzyme that in humans is encoded by the MGAT1 gene.
UDP-galactose translocator is a protein that in humans is encoded by the SLC35A2 gene.
Alpha-1,6-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase is an enzyme that in humans is encoded by the MGAT2 gene.
Lactosylceramide 4-alpha-galactosyltransferase is an enzyme that in humans is encoded by the A4GALT gene.
2-hydroxyacylsphingosine 1-beta-galactosyltransferase is an enzyme that in humans is encoded by the UGT8 gene.
Beta-1,4-galactosyltransferase 2 is an enzyme that in humans is encoded by the B4GALT2 gene.
Beta-1,4-galactosyltransferase 5 is an enzyme that in humans is encoded by the B4GALT5 gene.
Beta-1,3-galactosyltransferase 5 is an enzyme that in humans is encoded by the B3GALT5 gene.
Beta-1,4-galactosyltransferase 4 is an enzyme that in humans is encoded by the B4GALT4 gene.
Beta-1,4-galactosyltransferase 3 is an enzyme that in humans is encoded by the B4GALT3 gene.
Beta-1,3-galactosyltransferase 4 is an enzyme that in humans is encoded by the B3GALT4 gene.
Core 1 synthase, glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase, 1, also known as C1GALT1, is an enzyme which in humans is encoded by the C1GALT1 gene.
Glucosylceramide beta-1,4-galactosyltransferase is an enzyme with systematic name UDP-alpha-D-galactose:beta-D-glucosyl-(1<->1)-ceramide 4-beta-D-galactosyltransferase. This enzyme catalyses the following chemical reaction