RHODOPSIN MATURATION ANTAGONIZED BY DOMINANT RHODOPSIN MUTANTS

ninaE(D1), a dominant allele of the major Drosophila rhodopsin gene, e xpresses a rhodopsin that is predominantly recovered in a 80-kD comple x that likely represents rhodopsin dimers. By driving either ninaE(D1) or ninaE(+) expression from a heat-shock promoter, we show that the 8 0-kD rhodopsin complex forms immediately after gene activation. In wil d type, but not ninaE(D1), rhodopsin monomeric forms are detected at l ater times. The generation of monomeric forms of wild-type rhodopsin i s suppressed in vitamin A-deprived flies or in flies heterozygous for the dominant rhodopsin mutation. We also show that ninaE(D1) expressio n does not affect the maturation of another Drosophila visual pigment, Rh3. These results are consistent with the view that the ninaE(D1) rh odopsin antagonizes an early posttranslation process that is specific for maturation of the ninaE-encoded rhodopsin.