Plasmids expressing partial-length sense or antisense protein 4.1 RNA were microinjected into fertilized Xenopus eggs. Nuclease protection assays reveal that antisense protein 4.1 RNA lead to the specific loss of endogenous protein 4.1 transcripts after midblastula transition, with no effect on the levels of three unrelated transcripts. As a control, we show that this dramatic loss of endogenous protein 4.1 transcripts is blocked when fertilized eggs receive a second injection of plasmids that express partial-length sense protein 4.1 RNA. Immunocytochemistry of tadpole embryos with antibodies monospecific for protein 4.1 demonstrates that the antisense protein 4.1 RNA blocks the normal expression of protein 4.1 in embryos and interferes with the normal interdigitation of the photoreceptor outer segments with the pigment epithelium layer in the retina. These data suggest that reduced expression of a single membrane skeleton protein is sufficient to perturb normal cellular interactions of the retina.