Description

IPR036213 is a Calpain large subunit, domain III superfamily.

<p>This group of cysteine peptidases belong to the MEROPS peptidase family C2 (calpain family, clan CA). A type example is calpain, which is an intracellular protease involved in many important cellular functions that are regulated by calcium [[cite:PUB00002542], [cite:PUB00081544]]. The protein is a complex of 2 polypeptide chains (light and heavy), with eleven known active peptidases in humans and two non-peptidase homologues known as calpamodulin and androglobin [[cite:PUB00081545]]. These include a highly calcium-sensitive (i.e., micro-molar range) form known as mu-calpain, mu-CANP or calpain I; a form sensitive to calcium in the milli-molar range, known as m-calpain, m-CANP or calpain II; and a third form, known as p94, which is found in skeletal muscle only [[cite:PUB00002525]].</p> <p>All forms have identical light but different heavy chains. Both mu- and m-calpain are heterodimers containing an identical 28kDa subunit and an 80kDa subunit that shares 55-65% sequence homology between the two proteases [[cite:PUB00003577], [cite:PUB00002542]]. The crystallographic structure of m-calpain reveals six "domains" in the 80kDa subunit [[cite:PUB00000551], [cite:PUB00081543]]:</p> <ol> <li>A 19-amino acid NH2-terminal sequence;</li> <li>Active site domain IIa;</li> <li>Active site domain IIb. Domain 2 shows low levels of sequence similarity to papain; although the catalytic His has not been located by biochemical means, it is likely that calpain and papain are related [[cite:PUB00003577]].</li> <li>Domain III;</li> <li>An 18-amino acid extended sequence linking domain III to domain IV;</li> <li>Domain IV, which resembles the penta EF-hand family of polypeptides, binds calcium and regulates activity [[cite:PUB00003577]]. Ca²⁺-binding causes a rearrangement of the protein backbone, the net effect of which is that a Trp side chain, which acts as a wedge between catalytic domains IIa and IIb in the apo state, moves away from the active site cleft allowing for the proper formation of the catalytic triad [[cite:PUB00007140]].</li> </ol> <p>This superfamily describes domain III. Calpains are activated via rearrangement of the catalytic domain II induced by cooperative binding of Ca2+ to several sites of the molecule. A cluster of acidic residues in domain III, the acidic loop, has been proposed to function as part of an electrostatic switch in the activation process [[cite:PUB00086541]].</p>

This description is obtained from EB-eye REST.

Associated GO terms

Unable to find any GO terms for the transcript with the identifier.

Associated Lotus transcripts 3

Co-occuring domains 1

A list of co-occurring predicted domains within the L. japonicus gene space: