B4GALT1

Beta-1,4-galactosyltransferase 1 is an enzyme that in humans is encoded by the B4GALT1 gene.[5][6]

B4GALT1
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesB4GALT1, B4GAL-T1, CDG2D, GGTB2, GT1, GTB, beta4Gal-T1, beta-1,4-galactosyltransferase 1
External IDsOMIM: 137060 MGI: 95705 HomoloGene: 20378 GeneCards: B4GALT1
Orthologs
SpeciesHumanMouse
Entrez

2683

14595

Ensembl

ENSG00000086062

ENSMUSG00000028413

UniProt

P15291
Q86XA6

P15535

RefSeq (mRNA)

NM_001497

NM_022305
NM_001378519

RefSeq (protein)

NP_001488
NP_001365424
NP_001365425
NP_001365426

NP_071641
NP_001365448

Location (UCSC)Chr 9: 33.1 – 33.17 MbChr 4: 40.8 – 40.85 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

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.[6]

References

  1. GRCh38: Ensembl release 89: ENSG00000086062 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000028413 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. Lo NW, Shaper JH, Pevsner J, Shaper NL (Aug 1998). "The expanding beta 4-galactosyltransferase gene family: messages from the databanks". Glycobiology. 8 (5): 517–26. doi:10.1093/glycob/8.5.517. PMID 9597550.
  6. "Entrez Gene: B4GALT1 UDP-Gal:betaGlcNAc beta 1,4- galactosyltransferase, polypeptide 1".

Further reading


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