Calpain

**Definition:** Cysteine proteinase found in many tissues. Hydrolyzes a variety of endogenous proteins including NEUROPEPTIDES; CYTOSKELETAL PROTEINS; proteins from SMOOTH MUSCLE; CARDIAC MUSCLE; liver; platelets; and erythrocytes. Two subclasses having high and low calcium sensitivity are known. Removes Z-discs and M-lines from myofibrils. Activates phosphorylase kinase and cyclic nucleotide-independent protein kinase. This enzyme was formerly listed as EC 3.4.22.4.

**Tree numbers:** - D08.811.277.656.262.500.120 - D08.811.277.656.300.200.120

**Synonyms:** - Calcium-Activated Protease - Calcium-Dependent Neutral Proteinase - Desminase - Ca2+-Activated Protease - Calcium-Activated Neutral Proteinase - Calcium-Activated Neutral Protease - Calcium-Dependent Neutral Protease