Despite their functional and structural similarity, rods and cones also exhibit significant morphological and biochemical differences. These differences almost certainly reflect the cells' specialized functions, but they remain poorly understood. In this project, the cell biology of cone photoreceptors, and their relationship to the retinal pigment epithelium (RPE), is emphasized. Similarities and differences between the two photoreceptor classes will be examined in developing, mature, degenerating, and regenerating photoreceptors using immunocytochemical, autoradiographic, and lectin cytochemical techniques. In addition, changes in the localization and biosynthesis of photoreceptor proteins will be analyzed when the retina is experimentally detached from the RPE. Comparisons of regenerative capacity in primate rod and cone outer segments will be made. Opsin will be localized by immunoelectron microscopy in detached and reattached retinas. Interphotoreceptor retinol binding protein (IRBP) will be localized, and its biosynthesis will be compared in normal and detached retinas. Cellular retinaldehyde binding protein (CRALBP) will be tested for use as a specific cellular marker for migrating and/or proliferating RPE and Muller cells. The biosynthetic pathway for the transport, insertion, and diffusion of cone outer segment membrane proteins will be analyzed using electron microscope autoradiography. Lectin-gold conjugates will be used as ultrastructural probes to identify and quantify binding sites at the photoreceptor-RPE interface. Finally, the distribution of glycoconjugates at the photoreceptor-RPE interface, and their potential role in retinal adhesion, will be examined in retinas treated with a selective inhibitor of glycosylation (tunicamycin-B2).
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