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| {{STRUCTURE_1gx4| PDB=1gx4 | SCENE= }} | | {{STRUCTURE_1gx4| PDB=1gx4 | SCENE= }} |
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| '''ALPHA-,1,3 GALACTOSYLTRANSFERASE- N-ACETYL LACTOSAMINE COMPLEX'''
| | ===ALPHA-,1,3 GALACTOSYLTRANSFERASE- N-ACETYL LACTOSAMINE COMPLEX=== |
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| ==Overview==
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| Bovine alpha-1,3-galactosyltransferase (alpha3GT) catalyzes the synthesis of the alpha-galactose (alpha-Gal) epitope, the target of natural human antibodies. It represents a family of enzymes, including the histo blood group A and B transferases, that catalyze retaining glycosyltransfer reactions of unknown mechanism. An initial study of alpha3GT in a crystal form with limited resolution and considerable disorder suggested the possible formation of a beta-galactosyl-enzyme covalent intermediate (Gastinel, L. N., Bignon, C., Misra, A. K., Hindsgaul, O., Shaper, J. H., and Joziasse, D. H. (2001) EMBO J. 20, 638-649). Highly ordered structures are described for complexes of alpha3GT with donor substrate, UDP-galactose, UDP- glucose, and two acceptor substrates, lactose and N-acetyllactosamine, at resolutions up to 1.46 A. Structural and calorimetric binding studies suggest an obligatory ordered binding of donor and acceptor substrates, linked to a donor substrate-induced conformational change, and the direct participation of UDP in acceptor binding. The monosaccharide-UDP bond is cleaved in the structures containing UDP-galactose and UDP-glucose, producing non-covalent complexes containing buried beta-galactose and alpha-glucose. The location of these monosaccharides and molecular modeling suggest that binding of a distorted conformation of UDP-galactose may be important in the catalytic mechanism of alpha3GT.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12011052}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12011052 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12011052}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: N-acetyl lactosamine]] | | [[Category: N-acetyl lactosamine]] |
| [[Category: Transferase]] | | [[Category: Transferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 18:07:43 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 06:15:07 2008'' |