EC Number   |
General Information |
Reference |
|---|
   2.4.1.87 | evolution |
alpha1,3-galactosyltransferase gene displays unique evolutionary characteristics. This gene appeared early in mammalian evolution and is absent in other vertebrates. The alpha1,3GT gene is active in marsupials, nonprimate placental mammals, lemurs (prosimians) and New World monkeys, encoding the alpha1,3GT enzyme that synthesizes a carbohydrate antigen called alpha-gal epitope. The alpha-gal epitope is present in large numbers on cell membrane glycolipids and glycoproteins. The alpha1,3GT gene is inactivated in ancestral Old World monkeys and apes by frameshift single-base deletions forming premature stop codons. Because of this gene inactivation, humans, apes, and Old World monkeys lack alpha-gal epitopes and naturally produce an antibody called the anti-Gal antibody which binds specifically to alpha-gal epitopes and which is the most abundant antibody in humans. The evolutionary event that resulted in the inactivation of the alpha1,3GT gene in ancestral Old World primates might have been mediated by a pathogen endemic to Eurasia-Africa landmass that exerted pressure for selection of primate populations lacking the alpha-gal epitope. Once the alpha-gal epitope was eliminated, primates could produce the anti-Gal antibody, possibly as means of defense against pathogens expressing this epitope |
736656 |
| 2.4.1.87 | evolution |
the enzyme is a family 6 glycosyltransferase |
736317 |
| 2.4.1.87 | evolution |
the enzyme is a family 6 glycosyltransferase, family members have a nucleophilic residue (Glu317) situated close to the anomeric carbon |
736308 |
| 2.4.1.87 | malfunction |
absence of galactose-alpha-1,3-galactose residue in the GalT-KO pig cells results in a higher level of overall fucosylated N-glycans in GalT-KO pig fibroblasts compared to wild-type pig fibroblasts, the relative quantity of the N-glycolylneuraminic acid antigen is also slightly higher in the GalT-KO pigs, mutant phenotype, overview |
736808 |
| 2.4.1.87 | metabolism |
Otg proteins are involved in alpha1,3-galactosylation of O- and N-linked glycans |
-, 722792 |
| 2.4.1.87 | metabolism |
synthesis of biologically active oligosaccharides |
707367 |
| 2.4.1.87 | more |
identification and quantification of 47 N-glycans from wild-type and enzyme kockout pig fibroblasts using MALDI-TOF mass spectrometry, overview |
736808 |
| 2.4.1.87 | more |
reaction mechanism: substrate-assisted mechanism for retaining glycosyltransferases consisting of the stabilization of the developing negative charge on the beta-phosphate by the hydrogen of the attacking hydroxyl group of the acceptor molecule. This interaction is impaired in the alpha1,3-GalT reactants, which explains why Glu317 is required to nucleophilically assist initial catalysis by pushing leaving-group departure. The presence of Glu317 opens the door to the possibility of a double-displacement mechanism in GT6 family. In alpha1,3-GalT the substrate-assisted catalysis might be necessary in both mechanisms, because the nucleophilic strength of Glu317 is reduced by the interactions it makes to ensure proper acceptor binding. The same effect might be found in the absence of the acceptor when Glu317 interacts with water molecules, quantum mechanics/molecular mechanics dynamic simulations analysis, overview |
736308 |
| 2.4.1.87 | more |
the N-terminal loop is folded when the acceptor substrate is bound in the active site, substrate binding structure and analysis using ab initio quantum mechanics/molecular mechanics dynamic simulations, overview |
736317 |
| 2.4.1.87 | physiological function |
the wciN gene encodes a galactosyltransferase involved in the repeating unit assembly of Pneumococcus type 6B capsular polysaccharide |
721667 |
