Target size analysis of rhodopsin in retinal rod disk membranes.
Radiation inactivation of rhodopsin in situ using high-energy electrons gave a value for Mr of 20,200 by spectral assay, but 47,100 by assay of rhodopsin regeneration from opsin and 11-cis-retinal (sequence Mr = 38,840). No light/dark differences were seen. We conclude: (a) radiation inactivation measures the size of the functional unit, and the single hit hypothesis does not hold in our experiments; (b) 500 nm absorbance requires only about half the rhodopsin molecule to be intact, but reconstitution of rhodopsin from opsin requires the whole molecule; (c) we find no evidence for functional interactions between rhodopsin monomers in darkness or light.
D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D005136:Eye Proteins; D007425:Intracellular Membranes / Q000032:analysis; D008027:Light; D010786:Photoreceptor Cells / Q000032:analysis*; D012168:Retinal Pigments / Q000302:isolation & purification*; D012172:Retinaldehyde; D012243:Rhodopsin / Q000302:isolation & purification* / Q000528:radiation effects; D012374:Rod Cell Outer Segment / Q000032:analysis* / Q000528:radiation effects; D017299:Rod Opsins; D013053:Spectrophotometry
D005136:Eye Proteins; D012168:Retinal Pigments; D017299:Rod Opsins; D012243:Rhodopsin; D012172:Retinaldehyde