Mapping, Molecular Identification and Characterization of Ninag Affecting Rhodopsin Content in Drosophila Photoreceptors

Drosophila rhodopsin (Rh1) is the visual pigment of the photoreceptor cells. It is synthesized in the ER after which it undergoes post-translational modifications before being transported to the rhabdomere where it functions in phototransduction. In this study, I describe the identification of the Drosophila ninaG gene that affects rhodopsin content in the photoreceptors. Using deficiencies and P-element induced deletions, the ninaG gene was mapped to 86E4-86E6 cytological region on the third chromosome. Sequencing analysis of all fifteen genes within this region identified a stop codon in CG6728 gene in ninaGP330 mutant. To confirm this identification, I rescued the ninaG phenotype with a genomic fragment containing CG6728 ORF. CG6728 belongs to the glucose-methanol-choline (GMC) oxidoreductase family. NinaG protein is required in the eye for the transport of Rh1 from the ER to the rhabdomeres. My results show a specific and post-transcriptional role for NinaG in the biogenesis of Drosophila rhodopsin.