1qxp
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Crystal Structure of a mu-like calpain
OverviewOverview
The two Ca2+-dependent cysteine proteases, micro- and m-calpain, are, involved in various Ca2+-linked signal pathways but differ markedly in, their Ca2+ requirements for activation. We have determined the structure, of a micro-like calpain, which has 85% micro-calpain sequence (the first, 48 and the last 62 residues of the large subunit are those from m-calpain), and a low Ca2+ requirement. This construct was used because micro-calpain, itself is too poorly expressed. The structure of micro-like calpain is, very similar in overall fold to that of m-calpain as expected, but differs, significantly in two aspects. In comparison with m-calpain, the catalytic, triad residues in micro-like calpain, His and Cys, are much closer, together in the absence of Ca2+, and significant portions of the Ca2+, binding EF-hand motifs are disordered and more flexible. These structural, differences imply that Ca2+-free micro-calpain may represent a partially, activated structure, requiring lower Ca2+ concentration to trigger its, activation.
About this StructureAbout this Structure
1QXP is a Single protein structure of sequence from Rattus norvegicus. Active as Calpain-1, with EC number 3.4.22.52 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a micro-like calpain reveals a partially activated conformation with low Ca2+ requirement., Pal GP, De Veyra T, Elce JS, Jia Z, Structure. 2003 Dec;11(12):1521-6. PMID:14656436
Page seeded by OCA on Wed Nov 21 01:05:58 2007