Brain clathrin: immunofluorescent localization in rat retina.

By indirect immunofluorescence, the major protein of coated vesicles and coated pits was localized in rat retina. Specific fluorescence was circumscribed to regions containing synaptic endings in high density such as the cell internal plexiform layer (IPL) and external plexiform layer (EPL). Fine dots or patches of fluorescence were seen in the EPL. Weaker fluorescence was observed in the narrow cytoplasmic strips surrounding the large nucleus of the ganglion cell, internal nuclear and external nuclear cell layers. There was no fluorescent staining in the retinal pigment epithelium, a layer where active endocytosis of the outer segment of the rods and cones take place. The high concentration of clathrin found in the IPL and EPL is indicative of active recycling of synaptic membrane concomitant to neurotransmitter release and receptor molecule turnover.