OPSIN SUBSTITUTION INDUCED IN RETINAL RODS OF THE EEL (ANGUILLA-ANGUILLA (L)) - A MODEL FOR G-PROTEIN-LINKED RECEPTORS

Shifts in the wavelength of peak sensitivity of retinal rod photoreceptors of the eel (Anguilla anguilla (L.)) were induced by injection with human chorionic gonadotropin (HCG) and salmon pituitary extract. We demonstrate that these shifts, observed in single cells by microspectrophotometry and initiated by a single injection, are due to a change in the protein part of the rod visual pigment (opsin). Microspectrophotometry enabled us to follow the rate of opsin production and demonstrated that the new opsin is produced in existing rod outer segments. This inducible system featuring rapid receptor synthesis may be a useful model for the investigation of the expression and regulation of other visual pigments and diverse G-protein-linked cell membrane receptors.