ショウジョウバエ網膜の光応答機構

概要

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The phototransduction mechanism of Drosophila retina was studied using visual transduction mutant, norp A. This mutant has no receptor potential, although it has normal content of rhodopsin and inferior morphorogy in visual cells. We compared protein phosphorylation and phospholipid phosphorylation including phosphatidylinositol (PI) turnover between normal and mutant eyes. Membrane phosphorylation experiment showed that phospholipid phosphorylation was greatly altrered in the visual transduction mutant, whereas no change was observed in the normal fly retina. In the mutant retina, the activity of DG kinase, which is known as phosphorylating diacylglycerol (DG) to phosphatidic acid (PA) was found to be reduced extremely. On the other hand, phosphorylation of cytosol protein was not changed between normal and mutant eyes. We also found that PI specfic phospholipase C was absent, but activity of phospholipase A was not reduced in the mutant eyes. Gene dosage experiment revealed that DG kinase activity is parallel with rhabdomere size of Drosophila eye. Therefore, we can suggested that absence of PI specific phospholipase C is essential for the photoreceptor potential prodction.
日本膜学会の論文