Rhomboid proteases in mitochondria and plastids: Keeping organelles in shape

► Rhomboids are the most ancient family of intramembrane-cleaving proteases. ► The rhomboid domain of mammalian mitochondrial rhomboids is structurally similar to that of bacterial rhomboids. ► Whereas bacterial rhomboids use a dyad-based mechanism of catalysis, mitochondrial rhomboids might use a triad. ► Mitochondrial rhomboids regulate mitochondrial dynamics. ► Parl is emerging as a key regulator of mitochondrial quality control and seems implicated in Parkinson's disease.