Calcium-regulated non-lysosomal thiol-protease which catalyze limited proteolysis of substrates involved in cytoskeletal remodeling and signal transduction. Broad endopeptidase specificity. Binds 7 Ca(2+) ions. Activated by 200-1000 micromolar concentrations of calcium and inhibited by calpastatin. Forms a heterodimer with a small (regulatory) subunit (CAPNS1). Translocates to the plasma membrane upon Ca(2+) binding. Ubiquitous. Belongs to the peptidase C2 family.