1np8
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18-k C-terminally trunucated small subunit of calpain
OverviewOverview
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.
About this StructureAbout this Structure
1NP8 is a Single protein structure of sequence from Rattus norvegicus with CD as ligand. Full crystallographic information is available from OCA.
ReferenceReference
A second binding site revealed by C-terminal truncation of calpain small subunit, a penta-EF-hand protein., Leinala EK, Arthur JS, Grochulski P, Davies PL, Elce JS, Jia Z, Proteins. 2003 Nov 15;53(3):649-55. PMID:14579356
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