105] Renewal of lipids in rod outer segments

Abstract

Publisher Summary This chapter discusses the renewal of lipids in rod outer segments (ROS). The lipid and protein components of retinal ROS are constantly being renewed. The integral protein rhodopsin is synthesized in the inner segment and, after glycosylation, is transported to the base of the outer segment where it is incorporated into the basal infoldings of the plasma membrane. These infoldings eventually pinch off to form free-floating disks within which rhodopsin molecules remain until the disks reach the tip of the ROS and are shed and phagocytized by the retinal pigment epithelium, ROS lipids also are synthesized in the inner segment and are probably cotransported with newly synthesized opsin to the base of the growing outer segment. Because of the small amounts of lipids present in retinal extracts, in those instances where both neutral lipids and phospholipids contain radioactivity, both lipid classes should be separated on the same thin-layer plate.