Cleaves peptide substrates after methionine, leucine, and norleucine. Physiological substrates include EZR, alpha-tubulins and the apoptosis inhibitor BIRC5/Survivin. Promotes caspase activation and subsequent apoptosis of target cells. Granules of large granular lymphocytes. Highly and constitutively expressed in activated natural killer (NK) cells. Belongs to the peptidase S1 family. Granzyme subfamily.