β-Arrestin biosensors reveal a rapid, receptor-dependent activation/deactivation cycle

A series of FRET-based β-arrestin2 biosensors are used to study the dynamics and conformational changes that occur when β-arrestin2 binds to and dissociates from the β2-adrenergic receptor in living cells; results show that after β-arrestin2 dissociates from the β2-adrenergic receptor, it stays at the cell membrane in an active conformation for a while, indicating that β-arrestin is able to signal in a G-protein-coupled receptor (GPCR)-free state.