Fig. 7.
(a) Illustration of the proposed biological role of ABCA4. The left part of the diagram represents a ROS disk with a functional ABCA4, whereas the right part represents a ROS disk with an inactive ABCA4. Hexagons with carbon backbone denote all-trans-retinal (black) and all-trans-retinol (red). RDH: all-trans-retinol dehydrogenase 8. RPE: retinal pigment epithelium. See text for the description of the mechanism. (b) Schematic representations of rod and cone outer segments. Cone disks are open structures