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| {{STRUCTURE_1l9n| PDB=1l9n | SCENE= }} | | {{STRUCTURE_1l9n| PDB=1l9n | SCENE= }} |
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| '''Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation'''
| | ===Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11980702}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11980702 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11980702}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Transglutaminase]] | | [[Category: Transglutaminase]] |
| [[Category: X-ray structure]] | | [[Category: X-ray structure]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:42:07 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 12:02:24 2008'' |