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==Crystal Structure of Human Calpain-3 Protease Core in Complex with Leupeptin==
<StructureSection load='6bkj' size='340' side='right'caption='[[6bkj]], [[Resolution|resolution]] 3.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6bkj]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Streptomyces_roseus Streptomyces roseus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6BKJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6BKJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACE:ACETYL+GROUP'>ACE</scene>, <scene name='pdbligand=AR7:AMINO{[(4S)-4-AMINO-5,5-DIHYDROXYPENTYL]AMINO}METHANIMINIUM'>AR7</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6bkj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6bkj OCA], [https://pdbe.org/6bkj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6bkj RCSB], [https://www.ebi.ac.uk/pdbsum/6bkj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6bkj ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CAN3_HUMAN CAN3_HUMAN] Autosomal recessive limb girdle muscular dystrophy type 2A. The disease is caused by mutations affecting the gene represented in this entry.
== Function ==
[https://www.uniprot.org/uniprot/CAN3_HUMAN CAN3_HUMAN] Calcium-regulated non-lysosomal thiol-protease.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Limb-girdle muscular dystrophy type 2a arises from mutations in the Ca(2+)-activated intracellular cysteine protease calpain-3. This calpain isoform is abundant in skeletal muscle and differs from the main isoforms, calpain-1 and -2, in being a homodimer and having two short insertion sequences. The first of these, IS1, interrupts the protease core and must be cleaved for activation and substrate binding. Here, to learn how calpain-3 can be regulated and inhibited, we determined the structures of the calpain-3 protease core with IS1 present or proteolytically excised. To prevent intramolecular IS1 autoproteolysis, we converted the active-site Cys to Ala. Small-angle X-ray scattering (SAXS) analysis of the C129A mutant suggested that IS1 is disordered and mobile enough to occupy several locations. Surprisingly, this was also true for the apo version of this mutant. We therefore concluded that IS1 might have a binding partner in the sarcomere and is unstructured in its absence. After autoproteolytic IS1 removal from the active Cys-129 calpain-3 protease core, we could solve its crystal structures with and without the cysteine protease inhibitors E-64 and leupeptin covalently bound to the active-site cysteine. In each structure, the active state of the protease core was assembled by the cooperative binding of two Ca(2+) ions to the equivalent sites used in calpain-1 and -2. These structures of the calpain-3 active site with residual IS1 and with bound E-64 and leupeptin may help guide the design of calpain-3-specific inhibitors.

Structures of human calpain-3 protease core with and without bound inhibitor reveal mechanisms of calpain activation.,Ye Q, Campbell RL, Davies PL J Biol Chem. 2018 Jan 30. pii: RA117.001097. doi: 10.1074/jbc.RA117.001097. PMID:29382717<ref>PMID:29382717</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6bkj" style="background-color:#fffaf0;"></div>

==See Also==
*[[Calpain 3D structures|Calpain 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Streptomyces roseus]]
[[Category: Campbell RL]]
[[Category: Davies PL]]
[[Category: Ye Q]]