This gene encodes a member of the peptidase C1 (papain) family of cysteine proteases. Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed to generate multiple protein products. These products include the dipeptidyl peptidase 1 light, heavy, and exclusion domain chains, which together comprise one subunit of the homotetrameric enzyme. This enzyme has amino dipeptidase activity and may play a role in the activation of granzymes during inflammation. Homozygous knockout mice for this gene exhibit impaired granzyme activation and enhanced survival in a sepsis model. [provided by RefSeq, Aug 2015]