(570g) The Role of Cholesterol in Membrane Protein Activity

G-protein coupled receptors (GPCRs) represent the largest family of membrane proteins in the living world, and serve key roles in cellular signaling to diverse stimuli. For this reason, GPCRs are the largest target of therapeutics on the market. Despite this importance, our understanding of the relationship between structure and function, including downstream signaling, is rather limited. Since the first human GPCR, β₂-adrenergic receptor, was crystallized in 2007, a specific cholesterol binding site between helices I, II, III and IV – the cholesterol consensus motif (CCM) – was established, and as many as 25% of all class A GPCRs have been predicted to have a specific interaction with cholesterol. The role of the lipid environment including cholesterol may be very important in drug discovery and efficacy, and thus has been a focus of our laboratory.

For several years, we have been studying the role of cholesterol on the activity of the adenosine A_2A receptor (A_2AR), which is a class A GPCR whose natural ligands include adenosine and caffeine. In this talk, I will describe our studies of the role of bulk cholesterol on activity in human embryonic kidney (HEK-293) cells including ligand binding and downstream activity. I will also describe collaborative computational and experimental studies on mutagenesis of putative cholesterol interaction sites to test the specific interaction between cholesterol and A_2AR both at the CCM and alternative proposed interaction sites predicted by both coarse grain and atomistic simulations.