EFFECTS OF PHOSPHOLIPIDS IN LIVER MITOCHONDRIA OSMOTIC PROPERTIES AND BINDING OF CATIONS

1. 1. The function of phospholipid in determining the permeability and the cation-binding properties of the mitochondial membrane has been investigated. 2. 2. Mitochondria depleted of phospholipid by treatment in acetone, water and NH3 show a loss of their osmotic characteristics. When the phospholipid content is restored, the osmotic behavior of the mitochondria reappears both in ionic and in sucrose media. However, the reconstituted mitochondria cannot be rendered ion permeable by treatment with valinomycin (or gramicidin) at alkaline pH. 3. 3. Depletion of phospholipids causes a loss of the capacity of mitochondria to bind cations. The binding of cations is restored together with the restoration of the phospholipid content. 4. 4. Among the phospholipids tested, phosphatidyl ethanolamine is the most effective in restoring the osmotic properties as well as the cation-binding capacity of mitochondria. © 1969.