Pore-forming protein that plays a key role in granzyme-mediated programmed cell death, and in defense against virus-infected or neoplastic cells (  ). Plays an important role in killing other cells that are recognized as non-self by the immune system, e.g. in transplant rejection or some forms of autoimmune disease . Can insert into the membrane of target cells in its calcium-bound form, oligomerize and form large pores (, ). Promotes cytolysis and apoptosis of target cells by mediating the passage and uptake of cytotoxic granzymes ( , ). Facilitates the delivery of cationic cargo protein, while anionic or neural proteins are not delivered efficiently . Perforin pores allow the release of mature caspase-7 (CASP7) into the extracellular milieu (By similarity).
Subcellular locations: Cytolytic granule, Secreted, Cell membrane, Endosome lumen
Stored in cytolytic granules of cytolytic T-lymphocytes and secreted into the cleft between T-lymphocyte and target cell . Inserts into the cell membrane of target cells and forms pores . Membrane insertion and pore formation requires a major conformation change . May be taken up via endocytosis involving clathrin-coated vesicles and accumulate in a first time in large early endosomes .