Required for the control of apoptosis during postnatal growth. Essential for proteolytic processing of an antiapoptotic form of OPA1 which prevents the release of mitochondrial cytochrome c in response to intrinsic apoptotic signals (By similarity). Required for the maturation of PINK1 into its 52kDa mature form after its cleavage by mitochondrial-processing peptidase (MPP) (PubMed:22354088). Promotes changes in mitochondria morphology regulated by phosphorylation of P-beta domain (PubMed:14732705, PubMed:17116872). Cleaves type-1 transmembrane domains using a catalytic dyad composed of serine and histidine that are contributed by different transmembrane domains. Interacts with PSEN1 and PSEN2. Binds OPA1. Translocated into the nucleus by an unknown mechanism (PubMed:17116872). P-beta is proteolytically processed (beta-cleavage) in a PARL-dependent manner. The cleavage is inhibited when residues Ser-65, Thr-69 and Ser-70 are all phosphorylated. Belongs to the peptidase S54 family.