G protein-coupled receptors (GPCRs) are proteins containing seven membrane-spanning α- helices (7TMs) and form a major class of integral Membrane Proteins. Integral membrane proteins are difficult to study due to their inherent need for lipids as stabilizers of their structure and function. Detergent-solubilization of membrane proteins is often required for their extraction from the membrane. The choice of detergent may be crucial for retaining protein activity. Generally, Detergents should be used at a concentration above their critical micelle concentration (CMC) when working with membrane proteins. Micelles formed above the CMC mimic a membrane environment more closely. In GPCRs the greatest effect on receptor stability is observed with CHS (cholesterol hemisuccinate) and UPC (unsaturated phosphatidylcholine), where the optimal ratio of detergent to lipid was found to be 1.0:0.3 (Yao Z., Kobilka B, Anal. Biochem., 2005, 343:344-346). An often recommended mixture for the work with GPCRs consists of 50 mM Tris-HCl, 200 mM NaCl, 0.5% CHAPS, 0.1% CHS and 0.1% DDM.