1l9m: Difference between revisions
New page: left|200px<br /> <applet load="1l9m" size="450" color="white" frame="true" align="right" spinBox="true" caption="1l9m, resolution 2.10Å" /> '''Three-dimensional s... |
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[[Image:1l9m.gif|left|200px]]<br /> | [[Image:1l9m.gif|left|200px]]<br /><applet load="1l9m" size="350" color="white" frame="true" align="right" spinBox="true" | ||
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caption="1l9m, resolution 2.10Å" /> | caption="1l9m, resolution 2.10Å" /> | ||
'''Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation'''<br /> | '''Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation'''<br /> | ||
==Overview== | ==Overview== | ||
Transglutaminase (TGase) enzymes catalyze the formation of covalent | Transglutaminase (TGase) enzymes catalyze the formation of covalent cross-links between protein-bound glutamines and lysines in a calcium-dependent manner, but the role of Ca(2+) ions remains unclear. The TGase 3 isoform is widely expressed and is important for epithelial barrier formation. It is a zymogen, requiring proteolysis for activity. We have solved the three-dimensional structures of the zymogen and the activated forms at 2.2 and 2.1 A resolution, respectively, and examined the role of Ca(2+) ions. The zymogen binds one ion tightly that cannot be exchanged. Upon proteolysis, the enzyme exothermally acquires two more Ca(2+) ions that activate the enzyme, are exchangeable and are functionally replaceable by other lanthanide trivalent cations. Binding of a Ca(2+) ion at one of these sites opens a channel which exposes the key Trp236 and Trp327 residues that control substrate access to the active site. Together, these biochemical and structural data reveal for the first time in a TGase enzyme that Ca(2+) ions induce structural changes which at least in part dictate activity and, moreover, may confer substrate specificity. | ||
==About this Structure== | ==About this Structure== | ||
1L9M is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with BR, CL and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Protein-glutamine_gamma-glutamyltransferase Protein-glutamine gamma-glutamyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.2.13 2.3.2.13] Full crystallographic information is available from [http:// | 1L9M is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=BR:'>BR</scene>, <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Protein-glutamine_gamma-glutamyltransferase Protein-glutamine gamma-glutamyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.2.13 2.3.2.13] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1L9M OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: x-ray structure]] | [[Category: x-ray structure]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:42:50 2008'' | ||
Revision as of 14:42, 21 February 2008
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Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation
OverviewOverview
Transglutaminase (TGase) enzymes catalyze the formation of covalent cross-links between protein-bound glutamines and lysines in a calcium-dependent manner, but the role of Ca(2+) ions remains unclear. The TGase 3 isoform is widely expressed and is important for epithelial barrier formation. It is a zymogen, requiring proteolysis for activity. We have solved the three-dimensional structures of the zymogen and the activated forms at 2.2 and 2.1 A resolution, respectively, and examined the role of Ca(2+) ions. The zymogen binds one ion tightly that cannot be exchanged. Upon proteolysis, the enzyme exothermally acquires two more Ca(2+) ions that activate the enzyme, are exchangeable and are functionally replaceable by other lanthanide trivalent cations. Binding of a Ca(2+) ion at one of these sites opens a channel which exposes the key Trp236 and Trp327 residues that control substrate access to the active site. Together, these biochemical and structural data reveal for the first time in a TGase enzyme that Ca(2+) ions induce structural changes which at least in part dictate activity and, moreover, may confer substrate specificity.
About this StructureAbout this Structure
1L9M is a Single protein structure of sequence from Homo sapiens with , and as ligands. Active as Protein-glutamine gamma-glutamyltransferase, with EC number 2.3.2.13 Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions changes structure for activation., Ahvazi B, Kim HC, Kee SH, Nemes Z, Steinert PM, EMBO J. 2002 May 1;21(9):2055-67. PMID:11980702
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