1fr8 | pdb_00001fr8
CRYSTAL STRUCTURE OF THE BOVINE BETA 1,4 GALACTOSYLTRANSFERASE (B4GALT1) CATALYTIC DOMAIN COMPLEXED WITH URIDINE DIPHOSPHOGALACTOSE
Structural highlights
FunctionB4GT1_BOVIN The Golgi complex form catalyzes the production of lactose in the lactating mammary gland and could also be responsible for the synthesis of complex-type N-linked oligosaccharides in many glycoproteins as well as the carbohydrate moieties of glycolipids. The cell surface form functions as a recognition molecule during a variety of cell to cell and cell to matrix interactions, as those occurring during development and egg fertilization, by binding to specific oligosaccharide ligands on opposing cells or in the extracellular matrix. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedbeta1,4-galactosyltransferase T1 (beta4Gal-T1, EC 2.4.1.90/38), a Golgi resident membrane-bound enzyme, transfers galactose from uridine diphosphogalactose to the terminal beta-N-acetylglucosamine residues forming the poly-N-acetyllactosamine core structures present in glycoproteins and glycosphingolipids. In mammals, beta4Gal-T1 binds to alpha-lactalbumin, a protein that is structurally homologous to lyzozyme, to produce lactose. beta4Gal-T1 is a member of a large family of homologous beta4galactosyltransferases that use different types of glycoproteins and glycolipids as substrates. Here we solved and refined the crystal structures of recombinant bovine beta4Gal-T1 to 2.4 A resolution in the presence and absence of the substrate uridine diphosphogalactose. The crystal structure of the bovine substrate-free beta4Gal-T1 catalytic domain showed a new fold consisting of a single conical domain with a large open pocket at its base. In the substrate-bound complex, the pocket encompassed residues interacting with uridine diphosphogalactose. The structure of the complex contained clear regions of electron density for the uridine diphosphate portion of the substrate, where its beta-phosphate group was stabilized by hydrogen-bonding contacts with conserved residues including the Asp252ValAsp254 motif. These results help the interpretation of engineered beta4Gal-T1 point mutations. They suggest a mechanism possibly involved in galactose transfer and enable identification of the critical amino acids involved in alpha-lactalbumin interactions. Crystal structures of the bovine beta4galactosyltransferase catalytic domain and its complex with uridine diphosphogalactose.,Gastinel LN, Cambillau C, Bourne Y EMBO J. 1999 Jul 1;18(13):3546-57. PMID:10393171[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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