Tags: Enzyme.
Granzyme B is a serine protease most commonly found in the granules of cytotoxic lymphocytes (CTLs) natural killer cells (NK cells) and cytotoxic T cells. It is secreted by these cells along with the pore forming protein perforin to mediate apoptosis in target cells.Granzyme B has also more recently found to be produced by a wide range of non-cytotoxic cells ranging from basophils and mast cells to smooth muscle cells. The secondary functions of granzyme B are also numerous.