Study of the Structure of Rhodopsin during Photoactivation

Abstract

G-protein coupled receptors are a superfamily of transmembrane proteins that are heavily involved in signal transduction within cells. They are extremely important to study because they are involved in many physiological processes such as sight, smell, taste, etc. GPCRs are also heavily targeted by drugs and therefore understanding the way they function can help improvements with the development of drugs. This study uses Bovine Rhodopsin as a prototypical model GPCR, as it is very commonly studied. Rhodopsin has an inactive Metarhodopsin I and an active Metarhodopsin II state that allow for the functionality of the protein. The equilibrium that exists between the two states are studied in order to observe the structural features of the activation process. Changing the metal cofactors in solution, and varying the osmotic pressure, can cause a shift in the equilibrium. The effect these factors have on the shift are studied in these experiments. Analyzing the different Meta I and Meta II states can be done by using UV-visible spectroscopy. The different environments created by the factors listed above will be studied and can be applied to other GPCR proteins as well.