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1l9m
From Proteopedia
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(New page: 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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Revision as of 15:51, 12 November 2007
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Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation
Overview
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
1L9M is a Single protein structure of sequence from Homo sapiens with BR, CL and CA as ligands. Active as Protein-glutamine gamma-glutamyltransferase, with EC number 2.3.2.13 Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Mon Nov 12 17:58:03 2007
