FBS Colloquia No.274Laboratory of Single Molecule Biology

molecular bases of rod- and cone- specific photoresponses.

In the vertebrate retina, there are two types of photoreceptor cells: rods and cones. Both types of cells are responsible for converting light stimuli into visual neural information. It is known that rods and cones are responsible for vision in dim light (dark vision) and that in bright light (light vision), respectively, and thus have different sensitivity to light and response durations. We have been studying the molecular bases of the differences in photoresponses between cones and rods. As a result, we found there are differences in efficiencies of the enzymatic reactions working to form photoresponses, and these differences seems to cause the difference of photoresponses between rods and cones. On the other hand, the details of why these differences in efficiencies occur have not been clarified yet. We now think that this difference in efficiency may be due to differences in the lipid composition and distribution in the outer segments of photoreceptor cells. We will introduce the results that led us to this idea, and discuss future issues of our study.