A rapid, tag-free way to purify functional GPCRs

A GPCR purification method is described based on how the Galpha-CT (alpha5 helix) interacts with G-protein coupled receptors (GPCRs). The importance of this region in binding to and stabilizing the active GPCR state (R*) is well established, as it plays a conserved role in allosterically linking R* binding to Gα activation. Although only about 20 amino acids, the Galpha-CT contributes approximately 50% of the total interacting surface area with active receptors (R*). Galpha-CT binding also activates the G protein, by triggering conformational changes in the Galpha subunit that facilitate GDP – GTP exchange and heterotrimer dissociation.