Granzyme H

The Granzyme family of proteins belong to the larger peptidase S1 family. Granzyme A and granzyme B are serine proteases that facilitate apoptotic signaling in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. Within the granules of activated CTLs, granzyme A and granzyme B are processed and converted to their active forms by the lysosomal cysteine protease cathepsin C. Once cleaved, these active proteases target distinct substrates for proteolysis and, thereby, mediate apoptosis through two different pathways. Granzyme H, also designated cytotoxic T-lymphocyte proteinase, cathepsin G-like 2 (CTSGL2) or cytotoxic serine protease C (CSP-C), contains one peptidase S1 domain. Granzyme H localizes to cytoplasmic granules of cytolytic T-lymphocytes and is important for target cell lysis in cell-mediated immune responses.