Cyclophilin F (also known as Peptidylprolyl isomerase F, PPIF) is a member of peptidyl-prolyl cis-trans isomerase family. They are highly-conserved cytoplasmic enzymes that accelerate protein folding. This protein is part of the mitochondrial permeability transition pore in the inner mitochondrial membrane. Activation of this pore is thought to be involved in the induction of apoptotic and necrotic cell death.