Molecular Aspects of Photoreceptor Function in Stentor coeruleus

Abstract

Stentor coeruleus shows both step-up Photophobie and negative phototactic responses with maximum response to red light. Videotape recordings of these photoresponses have been made for illustration (in collaboration with D. Häder and K. L. Poff) . The photoreceptor has been isolated and characterized in terms of its chromophore structure and subunit organization of the protein. On the basis of preliminary results obtained from light-induced pH measurements and effects of ionophores on the Stentor photore- sponse, we propose a proton flux event as the primary mechanism of the Stentor photoreceptor.