title: Photophobic responses and phototaxis in Chlamydomonas are triggered by a single rhodopsin photoreceptor.
abstract: The rhodopsin nature of the photoreceptor for the behavioural light responses in Chlamydomonas has originally been revealed by action spectroscopy. Meanwhile most physiological experiments and the identification of all-trans-retinal in cell extracts favour that this chlamyrhodopsin contains an all-trans-type retinal chromophore with strong similarity to the light sensors SR I and SRII from Halobacteria. Reconstitution of retinal-deficient cells with [3H]retinal identified a single retinal protein with a MW of 30,000. Chlamyrhodopsin triggers a photoreceptor current in the eyespot region resulting in direction changes or phototaxis. Furthermore, when the light stimulus oversteps a critical level, two flagellar currents appear, which are the basis for photophobic responses. The physiological, electrophysiological and biochemical experiments suggest that all behavioural responses are triggered by a single rhodopsin-type receptor.
authors.affiliation: Institut für Biochemie, Universität Regensburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Kröger
authors.forename: P
authors.initials: P
authors.lastname: Hegemann
mesh_terms: D000818:Animals; D002465:Cell Movement; D002696:Chlamydomonas / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D012243:Rhodopsin / Q000502:physiology*
chemical_list: D012243:Rhodopsin