ABC seminar

Ari Koskelainen: Gain control of photoreceptor signaling in mammalian photoreceptor cells.

Signaling cascades in sensory cells can adjust their sensitivity to their input signal, e.g. odor or light, in response to varying background stimulation in order to extend their range of operation. Rod photoreceptors are extremely sensitive in darkness, being able to detect a single photon, but they can also remain responsive under surprisingly bright light. The ability to avoid saturation is achieved by regulating the sensitivity of rods to light under increasing ambient illumination levels. Calcium ions (Ca2+) play a major role in mediating the rapid sub-second scale light adaptation mechanisms. The principles and molecular mechanisms of photoreceptor signaling gain control will be discussed and evidence for a novel Ca2+-dependent mechanism contributing to the overall light adaptation capacity in mammalian rod photoreceptor cells will be presented.