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Crystal structure of M-CalpainCrystal structure of M-Calpain
Structural highlights
Function[CAN2_RAT] Calcium-regulated non-lysosomal thiol-protease which catalyze limited proteolysis of substrates involved in cytoskeletal remodeling and signal transduction. [CPNS1_RAT] Regulatory subunit of the calcium-regulated non-lysosomal thiol-protease which catalyzes limited proteolysis of substrates involved in cytoskeletal remodeling and signal transduction. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe combination of thiol protease activity and calmodulin-like EF-hands is a feature unique to the calpains. The regulatory mechanisms governing calpain activity are complex, and the nature of the Ca(2+)-induced switch between inactive and active forms has remained elusive in the absence of structural information. We describe here the 2.6 A crystal structure of m-calpain in the Ca(2+)-free form, which illustrates the structural basis for the inactivity of calpain in the absence of Ca(2+). It also reveals an unusual thiol protease fold, which is associated with Ca(2+)-binding domains through heterodimerization and a C(2)-like beta-sandwich domain. Strikingly, the structure shows that the catalytic triad is not assembled, indicating that Ca(2+)-binding must induce conformational changes that re-orient the protease domains to form a functional active site. The alpha-helical N-terminal anchor of the catalytic subunit does not occupy the active site but inhibits its assembly and regulates Ca(2+)-sensitivity through association with the regulatory subunit. This Ca(2+)-dependent activation mechanism is clearly distinct from those of classical proteases. Crystal structure of calpain reveals the structural basis for Ca(2+)-dependent protease activity and a novel mode of enzyme activation.,Hosfield CM, Elce JS, Davies PL, Jia Z EMBO J. 1999 Dec 15;18(24):6880-9. PMID:10601010[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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