Perforin

Perforin-1' is a is_associated_with::protein that in humans is encoded by the PRF1'' is_associated_with::gene.

Function
Perforin is a cytolytic protein found in the granules of Cytotoxic T lymphocytes (CTLs) and NK cells. Upon is_associated_with::degranulation, perforin inserts itself into the target cell's is_associated_with::plasma membrane, forming a pore. The lytic membrane-inserting part of perforin is the is_associated_with::MACPF domain. This region shares homology with cholesterol-dependent is_associated_with::cytolysins from Gram-positive bacteria.

Perforin has structural and functional similarities to is_associated_with::complement component 9 (C9). Like C9, this protein creates transmembrane is_associated_with::tubules and is capable of lysing non-specifically a variety of target cells. This protein is one of the main cytolytic proteins of cytolytic granules, and it is known to be a key effector molecule for T-cell- and natural killer-cell-mediated cytolysis. Perforin is thought to act by creating holes in the plasma membrane which triggers an influx of calcium and initiates membrane repair mechanisms. These repair mechanisms bring perforin and granzymes into early endosomes.

Clinical significance
Homozygous inheritance of defective PRF1 alleles result in the development of familial is_associated_with::hemophagocytic lymphohistiocytosis type 2 (FHL2), a rare and lethal autosomal recessive disorder of infancy.

Interactions
Perforin has been shown to interact with is_associated_with::calreticulin.