View source for 4js1


==crystal structure of human Beta-galactoside alpha-2,6-sialyltransferase 1 in complex with cytidine and phosphate==
<StructureSection load='4js1' size='340' side='right'caption='[[4js1]], [[Resolution|resolution]] 2.09&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4js1]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4JS1 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4JS1 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.09&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CTN:4-AMINO-1-BETA-D-RIBOFURANOSYL-2(1H)-PYRIMIDINONE'>CTN</scene>, <scene name='pdbligand=GAL:BETA-D-GALACTOSE'>GAL</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4js1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4js1 OCA], [https://pdbe.org/4js1 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4js1 RCSB], [https://www.ebi.ac.uk/pdbsum/4js1 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4js1 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SIAT1_HUMAN SIAT1_HUMAN] Transfers sialic acid from the donor of substrate CMP-sialic acid to galactose containing acceptor substrates.<ref>PMID:21081508</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Human beta-galactoside alpha-2,6-sialyltransferase I (ST6Gal-I) establishes the final glycosylation pattern of many glycoproteins by transferring a sialyl moiety to a terminal galactose. Complete sialylation of therapeutic immunoglobulins is essential for their anti-inflammatory activity and protein stability, but is difficult to achieve in vitro owing to the limited activity of ST6Gal-I towards some galactose acceptors. No structural information on ST6Gal-I that could help to improve the enzymatic properties of ST6Gal-I for biotechnological purposes is currently available. Here, the crystal structures of human ST6Gal-I in complex with the product cytidine 5'-monophosphate and in complex with cytidine and phosphate are described. These complexes allow the rationalization of the inhibitory activity of cytosine-based nucleotides. ST6Gal-I adopts a variant of the canonical glycosyltransferase A fold and differs from related sialyltransferases by several large insertions and deletions that determine its regiospecificity and substrate specificity. A large glycan from a symmetry mate localizes to the active site of ST6Gal-I in an orientation compatible with catalysis. The glycan binding mode can be generalized to any glycoprotein that is a substrate of ST6Gal-I. Comparison with a bacterial sialyltransferase in complex with a modified sialyl donor lends insight into the Michaelis complex. The results support an SN2 mechanism with inversion of configuration at the sialyl residue and suggest substrate-assisted catalysis with a charge-relay mechanism that bears a conceptual similarity to serine proteases.

The structure of human alpha-2,6-sialyltransferase reveals the binding mode of complex glycans.,Kuhn B, Benz J, Greif M, Engel AM, Sobek H, Rudolph MG Acta Crystallogr D Biol Crystallogr. 2013 Sep;69(Pt 9):1826-38. doi:, 10.1107/S0907444913015412. Epub 2013 Aug 17. PMID:23999306<ref>PMID:23999306</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4js1" style="background-color:#fffaf0;"></div>

==See Also==
*[[Sialyltransferase 3D structures|Sialyltransferase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Benz J]]
[[Category: Engel AM]]
[[Category: Greif M]]
[[Category: Kuhn B]]
[[Category: Rudolph MG]]
[[Category: Sobek H]]