3bow

Structure of M-calpain in complex with Calpastatin

spinqualitylabelsall models 3bow, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3bow is a 3 chain structure with sequence from Rattus norvegicus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA Related: 1df0, 1kfu, 1kxr Gene: Capn2 (Rattus norvegicus), Capns1, Capn4, Css1 (Rattus norvegicus), Cast (Rattus norvegicus) Activity: Calpain-2, with EC number 3.4.22.53 Resources: FirstGlance, OCA, RCSB, PDBsum Function [CAN2_RAT] Calcium-regulated non-lysosomal thiol-protease which catalyze limited proteolysis of substrates involved in cytoskeletal remodeling and signal transduction. [ICAL_RAT] Specific inhibition of calpain (calcium-dependent cysteine protease). Plays a key role in postmortem tenderization of meat and have been proposed to be involved in muscle protein degradation in living tissue. [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 PubMed Calpains are non-lysosomal calcium-dependent cysteine proteinases that selectively cleave proteins in response to calcium signals and thereby control cellular functions such as cytoskeletal remodelling, cell cycle progression, gene expression and apoptotic cell death. In mammals, the two best-characterized members of the calpain family, calpain 1 and calpain 2 (micro-calpain and m-calpain, respectively), are ubiquitously expressed. The activity of calpains is tightly controlled by the endogenous inhibitor calpastatin, which is an intrinsically unstructured protein capable of reversibly binding and inhibiting four molecules of calpain, but only in the presence of calcium. To date, the mechanism of inhibition by calpastatin and the basis for its absolute specificity have remained speculative. It was not clear how this unstructured protein inhibits calpains without being cleaved itself, nor was it known how calcium induced changes that facilitated the binding of calpastatin to calpain. Here we report the 2.4-A-resolution crystal structure of the calcium-bound calpain 2 heterodimer bound by one of the four inhibitory domains of calpastatin. Calpastatin is seen to inhibit calpain by occupying both sides of the active site cleft. Although the inhibitor passes through the active site cleft it escapes cleavage in a novel manner by looping out and around the active site cysteine. The inhibitory domain of calpastatin recognizes multiple lower affinity sites present only in the calcium-bound form of the enzyme, resulting in an interaction that is tight, specific and calcium dependent. This crystal structure, and that of a related complex, also reveal the conformational changes that calpain undergoes on binding calcium, which include opening of the active site cleft and movement of the domains relative to each other to produce a more compact enzyme. Calcium-bound structure of calpain and its mechanism of inhibition by calpastatin.,Hanna RA, Campbell RL, Davies PL Nature. 2008 Nov 20;456(7220):409-12. PMID:19020623 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Calpain

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