Calpain-1 catalytic subunit (CANP 1) is a protein that in humans is encoded by the CAPN1 gene.
The calpains, calcium-activated neutral proteases, are nonlysosomal, intracellular cysteine proteases. The mammalian calpains include ubiquitous, stomach-specific, and muscle-specific proteins. The ubiquitous enzymes consist of heterodimers with distinct large, catalytic subunits associated with a common small, regulatory subunit. This gene encodes the large subunit of the ubiquitous enzyme, calpain 1.
CAPN1 has been shown to interact with PSEN2.