1NP8

18-k C-terminally trunucated small subunit of calpain

Summary for 1NP8

• Entry DOI: 10.2210/pdb1np8/pdb
• Descriptor: Calcium-dependent protease, small subunit, CADMIUM ION (3 entities in total)
• Functional Keywords: dimer in solution, oligomer in crystal, hydrolase
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Cytoplasm: Q64537
• Total number of polymer chains: 2
• Total formula weight: 38162.61

Authors

Leinala, E.K.,Arthur, J.S.,Grochulski, P.,Davies, P.L.,Elce, J.S.,Jia, Z. (deposition date: 2003-01-17, release date: 2003-11-18, Last modification date: 2024-02-14)

Primary citation

Leinala, E.K.,Arthur, J.S.,Grochulski, P.,Davies, P.L.,Elce, J.S.,Jia, Z.
A second binding site revealed by C-terminal truncation of calpain small subunit, a penta-EF-hand protein
PROTEINS: STRUCT.,FUNCT.,GENET., 53:649-655, 2003

PubMed Abstract: The subunits in calpain and in the related penta-EF-hand (PEF) proteins are bound through contacts between the unpaired EF-hand 5 from each subunit. To study subunit binding further, a tetra-EF-hand 18 kDa N- and C-terminally truncated form of the calpain small subunit was prepared (18k). This protein does not combine with the calpain large subunit to form active calpain, but forms homodimers in solution, as shown by ultracentrifugation. The X-ray structure of the 18k protein in the presence of cadmium was solved to a resolution of 2.0 A. The structure of the monomer is almost identical to the known structure of the calpain small subunit, but the 18k protein forms an oligomer in the crystal by the use of two binding sites. One of these sites is an artefact arising from the C-terminal truncation, but the other is a naturally occurring site that is fully exposed to water in intact purified calpain. The characteristics of this site suggest that it may be important in binding other protein modulators involved in the regulation of calpain and of PEF proteins.

PubMed: 14579356
DOI: 10.1002/prot.10453

Experimental method

X-RAY DIFFRACTION (2 Å)