Granzyme A is a member of the granzyme family of the serine proteases found specifically in the cytotoxic granules of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. Granzyme A is the most abundant protease in CTL and NK cells. It induces caspase‑independent cell death when introduced into target cells by perforin. After being activated by lysyl endopeptidase, it cleaves a thioester substrate. Human granzyme A is synthesized as a precursor (262 residues) with a signal peptide (residues 1‑26), a propeptide (residues 27‑28) and a mature chain (residues 29‑262). The purified recombinant human Granzyme A consists of residues 26 to 262.