Gene encoding cytoskeletal proteins in Drosophila rhabdomeres

The ninaC gene is one of eight nina (neither inactivation nor afterpotential) genes identified from mutations that drastically reduce the amount of rhodopsin in the compound eye of Drosophila melanogaster. The gene has been cytogenetically localized to the 27E-28B region of the second chromosome. NaDodSO4/PAGE analysis of eye proteins of flies carrying one, two, or three copies of the ninaC region shows that two eye-specific proteins of molecular weight 170,000 and 130,000 display a strong dependence on the dosage of the ninaC gene, although the dependence is evident only when the dosage is decreased and not when it is increased. All mutations in the ninaC gene studied to date have pronounced effects on these two polypeptides. These results suggest that the ninaC locus encodes these two polypeptides. Ultrastructural studies show that the polypeptides encoded by ninaC are very likely to be important components of the cytoskeletal structure of rhabdomeral microvilli.