Isolation of a cDNA encoding a photoreceptor cell-specific actin-bundling protein: retinal fascin.

We have isolated a novel retina-specific gene, retinal fascin, encoding a new member of actin-bundling protein gene family, from a bovine retina cDNA library. The cDNA encodes a 492 amino acid protein which shows 36-57% amino acid identity with three vertebrate fascins, echinoid fascin and Drosophila singed gene. Northern blot analysis revealed that retinal fascin mRNA was exclusively expressed in the eye and not seen in other tissues examined. In situ hybridization analysis indicated that retinal fascin mRNA signals were found only in the inner segment of the photoreceptor layer and outer nuclear layer, indicating that retinal fascin was specifically expressed in photoreceptor cells. As fascins are actin-bundling proteins important for constructing several intracellular structures, retinal fascin might play a pivotal role in photoreceptor cell-specific events, such as disk morphogenesis.