The protein encoded by this gene is a member of the granzyme family. Members of this family are highly conserved serine proteases that eliminate transformed cells and virus-infected cells. This protein, which has chymotrypsin-like activity, has a preference for bulky aromatic amino acids at the P1 position and for acidic residues at the P3' and P4' positions. This protein is reported to be constitutively expressed in NK cells and may play a role in the cytotoxic arm of the innate immune response by inducing target cell death and by directly cleaving substrates in pathogen-infected cells. Alternative splicing results in multiple transcript variants that encode different protein isoforms.