IMMUNOLOCALIZATION OF X-ARRESTIN IN HUMAN CONE PHOTORECEPTORS

X-arrestin is a recently identified retina-specific gene of unknown fu nction, Affinity-purified anti-peptide antibody to human X-arrestin wa s prepared, and used in Western blot analysis of human retinal protein s and for immunohistochemistry on human retinal sections, By Western b lot analysis, the antibody specifically bound to an similar to 47 kDa protein, and by indirect immunofluorescence specifically labeled cone photoreceptors with greatest intensity in their outer segments, In sin gle and double label experiments, the localization of X-arrestin immun oreactivity was compared with immunolabeling patterns obtained with an tibodies to red/green cone opsin, rhodopsin, and S-antigen, The result s showed that X-arrestin is expressed in red-, green- and blue-sensiti ve cones in the human retina.