LIPID-METABOLISM IN PHOTORECEPTOR-MEMBRANES - REGULATION AND MECHANISMS

Lipid metabolism in photoreceptor rod outer segments has attracted con siderable attention because of its importance in providing the appropr iate environment for supporting an efficient phototransduction mechani sm. Recent studies suggest that lipid metabolism in these membranes is involved in the generation of second messengers and in signal transdu ction mechanisms. Phospholipid turnover is tightly regulated by phosph orylation-dephosphorylation reactions and light, and provides, in turn , with molecules capable of activating protein kinases and cellular pr ocesses such as membrane fusion or light-adaptation. These findings su ggest that photoreceptor membrane lipids are more than just important structural components of the visual cell rod outer segment.