Granulysin (GNLY) is a protein expressed in most mammals which functions as an antimicrobial peptide released by killer lymphocytes in cytotoxic granules. It is a pore-forming peptide, as it can puncture a microbial cell wall, allowing for other death-inducing enzymes to enter the microbe and cause microptosis. GNLY is inhibited by cholesterol, and is most effective in helping to kill cholesterol-deficient microbes.
It is part of the saponin-like protein family, and its gene is found on the 2nd chromosome in humans. It is distinguished by its 5 α-helical structure. Its expression is restricted to cytotoxic immune cells such as cytotoxic T cells, NK cells, NKT cells and γδ T cells. Orthologs of this protein are found in most mammal species, such as in cows and pigs, however not in rodents.
Granulysin is also an active player in many diseases, including leprosy and toxic epidermal necrolysis.
