Mitochondria are essential organelles whose functional integrity depends on a defined lipid composition of its membranes. The accumulation of phospholipids within mitochondria depends on interorganellar lipid transport between the ER and mitochondria, intramitochondrial phospholipid trafficking events and on the synthesis of cardiolipin or phosphatidylethanolamine within the organelle.
We examine the function of prohibitins in the inner membrane of mitochondria which form large ring complexes and are thought to act as membrane scaffolds. Loss of prohibitins leads to severe mitochondrial deficiencies and causes neurodegeneration in mice. Genetic interaction studies in yeast link the function of prohibitins to the mitochondrial phospholipid metabolism and suggest that prohibitins may act both as protein and lipid scaffold for cardiolipin and phosphatidylethanolamine within mitochondrial membranes. The analysis of genes genetically interacting with prohibitins led to the identification of a novel regulatory circuit within mitochondria that determines the phospholipid composition of mitochondrial membranes.