Abstract
It has been established that light stimulus depolarizes (invertebrate) or hyperpolarizes (vertebrate) photoreceptor cells by modulating the Na+ permeability of the cell membranes. The primary event in vision resides in a photon hitting the visual pigmellt, rhodopsin. However, the intermediate process linking rhodopsin bleaching to the opening or closing of the light dependent Na+ channel remains obscure. An effort to use Drosophila mutations for the study of this intermediate process is described. Two-dimensional gel electrophoretic analyses of a visual transduction mutation, norp A, suggested that three classes of retina-specific polypeptides in Drosophila and their light-dependent phosphorylation are involved in the visual process.
