PARL is a mitochondrial integral membrane protein and a member of the highly conserved rhomboid superfamily of membrane proteins. PARL is required for the control of apoptosis during postnatal growth and is required for the processing of OPA1, a protein that prevents the release of cytochrome C from the mitochondria in response to apoptotic signals. In lymphocytes and neurons, PARL’s association with other proteins, such as the Bcl-2 family-related protein Hax1 and Omi can lead to the proteolytic processing of Omi by PARL, preventing the accumulation of Bax, thereby suppressing apoptosis. Variations in this gene have been associated with increased risk for type 2 diabetes. PARL may also play a role in the progression of Alzheimer’s disease through its associations with presenilin-1 and -2. Despite its predicted molecular weight of ~42kDa, PARL is observed at a higher molecular weight in SDS-PAGE. Multiple isoforms of PARL are known to exist.