Table 1. Combinations of fluorophores for studying GPCR–protein complexes using FRET.

Cy3, indocarbocyanine; RFP/DsRed, red fluorescent protein; TrITC, tetramethylrhodamine isothiocyanate.

	Donor	Acceptor	References
Fusion proteins	CFP*	GFP*	[61]
	CFP*	YFP*	[27,33,34,44,50,60,61,69,95]
	GFP*	RFP/DsRed	[26,69]
	GFP*	YFP*	[16,53,73,94]
	YFP*	RFP	[12]
Conjugated to antibodies	Europium chelate	Allophycocyanin	[16,20–22]
	Europium cryptate	Alexa Fluor 647	[17,18]
	FITC/fluorescein	Rhodamine	[13–15,19]
Fusion protein and conjugated to antibody	GFP*	Cy3	[23]
Conjugated to ligands	FITC	Texas Red	[15]
	FITC	TrITC	[24]

* Note that GFP variants may or may not be ‘enhanced’ to improve expression, cellular solubility and/or stability, such as EGFP/GFP², ECFP and EYFP. For simplicity, these proteins are referred to as GFP, CFP and YFP respectively, as commonly occurs in the FRET literature. Data on excitation and emission peaks can be obtained from the Zeiss Corporation website (http://www.zeiss.com).