Determining the binding affinity of agonists to bitter taste receptors using frequency locked microtoroid resonators

G-protein coupled receptors (GPCRs) play a crucial role in signal transduction in eukaryotic cells. Bitter taste receptors (TAS2Rs) are one type of GPCR and are responsible for detecting bitterness which is key for protecting organisms from potential toxic substances. Moreover, TAS2Rs have been found in many tissues in the human body, including the GI tract, heart, and brain. TAS2R5 is a bitter taste receptor expressed in the tongue smooth muscle and palate epithelia which has agonists that have a strong impact on the treatment of asthma and chronic obstructive pulmonary disease. We utilize a label-free, highly sensitive, and specific optical resonator biosensing technique known as FLOWER (frequency locked optical whispering evanescent resonator) to measure the binding affinity of three different agonists to the TASR5 bitter taste receptor and determine their relative potencies.