Direct zinc binding to purified rhodopsin and disc membranes.
Using the radionuclide 65Zn, we have demonstrated the direct binding of zinc to purified rhodopsin. 65Zn is eluted with detergent-solubilized rhodopsin from concanavalin A columns and remains bound to the visual pigment through a subsequent gel-filtration step. Zinc binding to purified disc membranes is highly specific and, of the ions tested, copper is the best competitor. Equilibrium-dialysis experiments indicate that zinc binding to detergent-solubilized forms of rhodopsin may increase on bleaching the photopigment. These results may have important implications for studies that indicate that zinc plays a role in retinal degeneration and normal photoreceptor physiology.
Shuster
T A
TA
Department of Anatomy and Physiology, California State University, Long Beach 90840.
Nagy
A K
AK
Conly
D C
DC
Farber
D B
DB
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D002417:Cattle; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003624:Darkness; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008027:Light; D012243:Rhodopsin / Q000302:isolation & purification / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*; D015037:Zinc Radioisotopes
D002413:Cations, Divalent; D015037:Zinc Radioisotopes; D012243:Rhodopsin; D015032:Zinc; D002118:Calcium