This gene encodes a member of the cysteine peptidase family C13 that plays an important role in the endosome/lysosomal degradation system. The encoded inactive preproprotein undergoes autocatalytic removal of the C-terminal inhibitory propeptide to generate the active endopeptidase that cleaves protein substrates on the C-terminal side of asparagine residues. Mice lacking the encoded protein exhibit defects in the lysosomal processing of proteins resulting in their accumulation in the lysosomes, and develop symptoms resembling hemophagocytic lymphohistiocytosis.