Binding of Gq protein stabilizes the activated state of the muscarinic receptor type 1

► G protein binding has been reported to stabilize the active conformation of GPCR. ► We investigated the effects on the active conformation of the M1R FRET construct. ► Gq protein decelerated the transition from active to quiescent state of the M1R. ► Gq binding stabilizes the active conformation of the M1R.