Granzyme H (E3H7W) Rabbit mAb #99695

Granzymes are a family of serine proteases expressed by cytotoxic T lymphocytes and natural killer (NK) cells and are key components of immune responses to pathogens and transformed cells (1). Granzymes are synthesized as zymogens and are processed into mature enzymes by cleavage of a leader sequence. They are released by exocytosis in lysosome-like granules containing perforin, a membrane pore-forming protein. Granzyme B has the strongest apoptotic activity of all the granzymes as a result of its caspase-like ability to cleave substrates at aspartic acid residues thereby activating procaspases directly and cleaving downstream caspase substrates (2,3).
Granzyme H has chymotrypsin-like thioester activity with a preference for hydrophobic, aromatic amino acid residues, such as phenylalanine, tyrosine, or methionine, at the P1 site (4,5). Granzyme H is predominantly expressed at high levels in NK cells, but not in T lymphocytes, and has also been described in mast cells (6-8). After perforin-mediated entry into a target cell, Granzyme H induces many hallmarks of programmed cell death, such as mitochondrial depolarization, generation of reactive oxygen species, DNA degradation, and chromatin condensation (9,10).