Abstract
A natural calpain activator protein has been isolated from bovine brain and characterized in its properties and molecular structure. The protein is a homodimer with a molecular mass of about 30 kDa and results in being almost identical to UK114 goat liver protein. Significant similarities with mouse HR12 protein were also observed, whereas a lower degree of similarity was found with a family of heat-responsive proteins named YJGF and YABJ from Haemophilus influenzae and Bacillus subtilis, respectively. The brain activator expresses a strict specificity for the mu-calpain isoform, being completely ineffective on the m-calpain form. As expected, also UK114 was found to possess calpain-activating properties, indistinguishable from those of bovine brain activator. A protein showing the same calpain-activating activity has been also isolated from human red cells, indicating that this factor is widely expressed. All these activators are efficient on mu-calpain independently from the source of the proteinase. The high degree of specificity of the calpain activator for a single calpain isoform may be relevant for the understanding of sophisticated intracellular mechanisms underlying intracellular proteolysis. These data are indicating the existence of a new component of the Ca2+-dependent proteolytic system, constituted of members of a chaperonin-like protein family and capable of promoting intracellular calpain activation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.