Dr. Osawa's research is supported by grants from the National Institutes of Health. My overall research interest is to study the regulatory mechanisms of signal transduction by G protein-coupled receptors using the visual system as a model. Two types of photoreceptor cells, rods and cones, mediate the response to light in the mammalian retina.
Rods are responsible for vision in dim light through rhodopsin.
Cones are specialized to detect red, blue or green light through the presence of distinct light-absorbing opsins. Electrophysiological studies have determined that the response to light is more rapid in cones and that they recover more quickly than rods. The reasons for these differences are not well understood. Although a number of the cone-specific proteins have been cloned, there have been very few in vitro reconstitution studies to determine whether these proteins interact similarly to their rod cell counterparts. My research addresses the reasons for the differences in signal termination observed for rods and cones by examining the process of receptor desensitization.