1np8
18-k C-terminally trunucated small subunit of calpain18-k C-terminally trunucated small subunit of calpain
Structural highlights
Function[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 PubMedThe 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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