Nanobody stabilization of G protein-coupled receptor conformational states

► Last four years, several inactive-state GPCR structures have been solved. ► Active-state structures may be unstable without a native signaling partner. ► Nanobodies act as surrogates of GPCR signaling partners. ► Nanobody 80 has G protein-like properties and stabilizes an agonist activated state of the β2AR.