Elizabeth Fear, Horizon Honors High School (research conducted at the University of Arizona)
Effect of Hydration on Rhodopsin Activation
Rhodopsin, responsible for vision under dim light, is a prominent member of the G-Protein Coupled Receptor (GPCR) protein class which is targeted by a third of all pharmaceuticals. Two states of rhodopsin exist in physiological equilibrium: active and inactive. We hypothesized that hydration plays a crucial role in the shift to the active conformation. The fraction of active rhodopsin is quantified via UV-visible absorbance spectroscopy upon light exposure in the presence of various dehydrating osmolytes that generate osmotic pressure. We found that water does play an influential role in rhodopsin activation and that dehydration with osmotic stress favors the inactive state. As countless physiological processes involve GPCRs, greater insight into the relationship between water and rhodopsin activation can enable treatments of GPCR dysfunction across human anatomy.