Figure 2.

Double immunolabeling of X. laevis photoreceptors with anti–xlProminin-1 N terminus antibody αPN and anti–α-tubulin antibody. Sections of X. laevis retina were double immunolabeled with αPN and anti–acetylated α-tubulin antibody. (A) The COS is brightly labeled with αPN (green) predominantly on one side (arrows). The base of the ROS is also faintly labeled with αPN as a thin band (arrowheads). Distal ROS is diffusively labeled with αPN at low intensity. The labeling intensity of αPN on COS is much greater than on ROS. (B) The same section of retina was labeled with anti–acetylated α-tubulin antibody (red). Axonemes of the connecting cilia of both rods (arrowheads) and cones (arrows) are labeled with that antibody. (C) A longitudinally sectioned cone cell on the upper part of the image shows clearly separated labeling of xlProminin-1 and α-tubulin. Labeling of αPN on the rims is confined to one side of the COS (arrowhead). A differently oriented cell is also seen on the lower left. (D) Nomarski view of the same retina section to show the morphology of cells. (E) Superimposed image to show the relative position of αPN and anti–α-tubulin immunolabeling. αPN labels the lamellar rims opposite the axoneme of the COS. (F) Cross-section of a tadpole retina labeled with αPN (green) and Texas Red-X conjugated wheat germ agglutinin (red) that binds to glycosylated photopigments. The semicircular pattern of αPN labeling is readily seen in the cross-sectioned COS (arrows), further demonstrating the asymmetrical distribution of xlProminin-1 in this organelle. Scale bars: 2 μm (A, B, D, E); 5 μm (C, F).