Phosrestins I and II: Arrestin homologs which undergo differential light-induced phosphorylation in the [formula omitted] photoreceptor in vivo

Abstract

The 49-kDa phosphoprotein gene and Dmarrestin gene encode two distinct arrestin homologs in the Drosophila photoreceptor. We find that two DNA fragments representing the Dmarrestin gene hybrid-selected a mRNA the in vitro translation of which produced a protein corresponding to the 39-kDa phosphoprotein previously reported by us. We propose to name these phosphorylated homologs of arrestin phosrestin I (49-kDa protein) and phosrestin II (39-kDa protein or the Dmarrestin gene product). We find that phosrestins I and II follow different time courses of phosphorylation in vivo ; in the time period (∼seconds) during which 43% of phosrestin I became phosphorylated, the phosphorylated state of phosrestin II remained unchanged from that of the nonilluminated flies. These results indicate that phosrestins I and II probably occupy different functional roles in the Drosophila photoreceptor.