2gam: Difference between revisions

[[Image:2gam.gif|left|200px]]<br /><applet load="2gam" size="350" color="white" frame="true" align="right" spinBox="true"  

Leukocyte type core 2 beta1,6-N-acetylglucosaminyltransferase (C2GnT-L) is a key enzyme in the biosynthesis of branched O-glycans. It is an inverting, metal ion-independent family 14 glycosyltransferase that catalyzes the formation of the core 2 O-glycan (Galbeta1-3[GlcNAcbeta1-6]GalNAc-O-Ser/Thr) from its donor and acceptor substrates, UDP-GlcNAc and the core 1 O-glycan (Galbeta1-3GalNAc-O-Ser/Thr), respectively. Reported here are the x-ray crystal structures of murine C2GnT-L in the absence and presence of the acceptor substrate Galbeta1-3GalNAc at 2.0 and 2.7A resolution, respectively. C2GnT-L was found to possess the GT-A fold; however, it lacks the characteristic metal ion binding DXD motif. The Galbeta1-3GalNAc complex defines the determinants of acceptor substrate binding and shows that Glu-320 corresponds to the structurally conserved catalytic base found in other inverting GT-A fold glycosyltransferases. Comparison of the C2GnT-L structure with that of other GT-A fold glycosyltransferases further suggests that Arg-378 and Lys-401 serve to electrostatically stabilize the nucleoside diphosphate leaving group, a role normally played by metal ion in GT-A structures. The use of basic amino acid side chains in this way is strikingly similar to that seen in a number of metal ion-independent GT-B fold glycosyltransferases and suggests a convergence of catalytic mechanism shared by both GT-A and GT-B fold glycosyltransferases.

2GAM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Active as [http://en.wikipedia.org/wiki/Beta-1,3-galactosyl-O-glycosyl-glycoprotein_beta-1,6-N-_acetylglucosaminyltransferase Beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-N- acetylglucosaminyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.102 2.4.1.102] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GAM OCA].  

[[Category: Pak, J E.]]

[[Category: Rini, J M.]]

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