We report studies of the in vitro regeneration of Rh1 Drosophila rhodopsin using immunochemical and spectroscopic probes for the release of arrestin (49 kDa). Upon illumination of metarhodopsin-containing membrane suspensions isolated from homogenized Drosophila heads, arrestin was released into the aqueous medium. In contrast, no release of arrestin was observed upon illumination of metarhodopsin in lipid/detergent micellar extracts. The spectroscopic changes associated with the transition from metarhodopsin to rhodopsin were, however, similar in membrane suspensions and in micellar extracts. The light-driven release of arrestin was restored in reconstituted liposomes formed by dialysis of detergent from the micellar extracts. We conclude that micellar solubilization of membranes decouples the light- driven release of arrestin from rhodopsin structural changes which are responsible for altering the λ(max) of the chromophore. The finding that arrestin release from rhodopsin can be modulated by changes in the local membrane environment provides an opportunity to further characterize the nature of rhodopsin conformational changes during regeneration.
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