Pitrilysin metalloproteinase 1 (PITRM1) is an ATP-independent protease that degrades mitochondrial transit peptides after their cleavage. PITRM1 also degrades other unstructured peptides. It is specific for peptides in the range of 10 to 65 residues. It is able to degrade amyloid beta A4 (APP) protein when it accumulates in mitochondrion, suggesting a link with Alzheimer disease. PTMRM shows a preference for cleavage after small polar residues and before basic residues, but without any positional preference [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/Q5JRX3].