ABSTRACT
The benets of mitochondrial membrane unsaturation are highlighted here. As background, scientists in the 1970s were rst able to calibrate the physical speed of the essential light-sensing protein rhodopsin embedded in docosahexaenoic acid (DHA)-enriched membrane disks (i.e., rhodopsin disks) of rod cells of the eye (Poo and Cone, 1974; Liebman and Entine, 1974; Litman et al., 2001). These now classic studies demonstrate that the light-sensing protein rhodopsin rotates and moves laterally across the surface of membrane disks at amazing speeds. The motional properties of the integral membrane protein rhodopsin were calibrated using micro-lasers; for example, rhodopsin was found to rotate in a molecular swirl timed at 0.00002 s per turn. This remains the speed record for a full swing of a membrane-bound protein and links highly unsaturated phospholipids with extreme motion of membrane components. Lateral motion of rhodopsin across the surface of membrane disks is also extremely fast and is essential in triggering the visual cascade. By analogy, we suggest that the unique conformational dynamics of polyunsaturated fatty acids (PUFAs) in mitochondrial membranes are harnessed to maximize motion of components of the electron transport chain, resulting in enhanced energy production. We dene motion of mitochondrial membranes in terms of mobility of membrane lipids, proteins, and the lipophilic electron carrier ubiquinone-properties that enable energy production.
