TABLE 3.

Sensors discussed in Section 4 for detection of beta-arrestin (β-arr) and GPCR kinase (GRK) recruitment to GPCRs and β-arr conformational change.

Sensor type	GPCR signalling step	Detection method/mechanism	References
Intermolecular beta-arrestin sensor	β-arr recruitment to GPCR	RLuc/YFP BRET	Angers et al. (2000)
		RLuc/EYFP BRET	Kroeger et al. (2001)
		ECFP/EYFP FRET	Kraft et al. (2001)
		FlAsH/ReAsH FRET	Zurn et al. (2010)
		NanoBiT complementation assay	Dixon et al. (2016), He et al. (2018)
	β-arr recruitment to membrane	RLuc/citrine BRET	Clayton et al. (2014)
		RLuc/rGFP BRET	Namkung et al. (2016)
		Split NanoLuc complementation assay	Hauge Pedersen et al. (2021)
Intermolecular GRK sensor	GRK recruitment to GPCR	RLuc/YFP BRET	Hasbi et al. (2004)
		RLuc/GFP BRET	Jorgensen et al. (2008)
Intramolecular beta-arrestin RET sensor	β-arr conformational change	RLuc/YFP BRET	Charest et al. (2005)
		RLuc/FlAsH BRET	Lee et al. (2016)
		NanoLuc/CyOFP1 BRET	Oishi et al. (2020)
		CFP/FlAsH FRET	Nuber et al. (2016)