1NX2: Calpain Domain Vi

The Ca(2+)-dependent cysteine protease calpain along with its endogenous inhibitor calpastatin is widely distributed. The interactions between calpain and calpastatin have been studied to better understand the nature of calpain inhibition by calpastatin, which can aid the design of small molecule inhibitors to calpain. Here we present the crystal structure of a complex between a calpastatin peptide and the calcium-binding domain VI of calpain. DIC19 is a 19 residue peptide, which corresponds to one of the three interacting domains of calpastatin, which is known to interact with domain VI of calpain. We present two crystal structures of DIC19 bound to domain VI of calpain, determined by molecular replacement methods to 2.5A and 2.2A resolution. In the process of crystallizing the inhibitor complex, a new native crystal form was identified which had the homodimer 2-fold axis along a crystallographic axis as opposed to the previously observed dimer in the asymmetric unit. The crystal structures of the native domain VI and its inhibitor PD150606 (3-(4-iodophenyl)-2-mercapto-(Z)-2-propenoic acid) complex were determined with the help of molecular replacement methods to 2.0A and 2.3A resolution, respectively. In addition, we built a homology model for the complex between domain IV and DIA19 peptide of calpastatin. Finally, we present a model for the calpastatin-inhibited calpain.
PDB ID: 1NX2Download
MMDB ID: 24083
PDB Deposition Date: 2003/2/7
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 1NX2: dimeric; determined by author and by software (PISA,PQS)
Molecular Components in 1NX2
Label Count Molecule
Proteins (2 molecules)
Calcium-dependent Protease, Small Subunit(Gene symbol: CAPNS1)
Molecule annotation
Chemicals (8 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB