Abstract
Localization of fodrin and α-actinin in the rat retinal pigment epithelium (RPE) in vivo was examined by immunolabeling of frozen sections as well as en face preparations. Fodrin was found densely in the apical cytoplasm and in the basal infolding; it was sparse in the lateral cell membrane and hardly present in the microvillus. On the other hand, α-actinin was concentrated in the dense material underlying the zonula adherens. Notably the protein was also seen along the microfilament bundle arising from the junction; it was present continuously in the vicinity of the junction, but localized only in electron-dense bodies deep in the cytoplasm. Fodrin was seen on both sides of the bundle but not in the bundle itself.
The present results showed that the distribution of fodrin and α-actinin in RPE is distinctive among simple epithe1ia; fodrin is more concentrated in the basal cell membrane than in the lateral cell membrane; α-actinin is present in the actin filament bundle running through the apical cytoplasm and not in the terminal web. These differences are likely to be related to the specialized function and location of RPE.
