Granzyme A (Granzyme A) is a member of the granzyme family of serine proteases and is found exclusively in the granules of cytotoxic T-lymphocytes (CTL) and natural killer (NK) cells.Granzyme A is the most abundant protease in CTL and NK cells. It enters target cells via perforin, which in turn induces caspase-independent cell death. Upon activation by lysyl peptide chain endonuclease, Granzyme A cleaves thioester substrates. Human Granzyme A is synthesized as a precursor (262 residues) that carries a signal peptide (residues 1-26), a prepeptide (residues 27-28) and a mature chain (residues 29-262). Purified recombinant human Granzyme A consists of residues 26-262.