Calpain-2 participates in the process of calpain-1 inactivation by Shinkai-Ouchi et al.
Calpain belongs to the calcium-dependent non-lysosomal cysteine protease. Calpain-1 and calpain-2 expression are ubiquitous in mammals and an important mediator of the action of calcium. Specific substrate cleavage by calpain-1 and calpain-2 is critical for several calcium-dependent cellular pathways including neuronal function, muscle contraction, signal transduction, cell differentiation, proliferation, and apoptosis.Research suggests that calpain-1 and calpain-2 perform similar functions due to their structurally highly similar isoforms. Increasing evidence suggests that calpain-1 and calpain-2 carry out their specific function in vivo. A recent paper published by Shinkai-Ouchi et al. (Bioscience Reports (2020) 40, https://doi.org/10.1042/BSR20200552) elucidated the mechanism to differentiate the function of each calpain in respect to the efficiency and longevity for proteolysis after activation. Further, the study represented that calpain-1 and calpain-2 do not synergistically perform their workin vitro. On the other hand, the activity of calpain-1 is reduced in presence of calpain-2. This insight establishes the platform for future studies to examine how calpain-2 regulates the calpain-1 for substrate proteolysis.