Table 1.

The use of protein tags in some applicative examples.

Applications	FPs	Affinity Tag	SNAP-Tag	Notes
In vivo imaging	+ a		+
Substrate utilization	+	−	−	FPs do not need of any substrate for their fluorescence
Emission spectra	±	−	+	FPs are in a limited number with respect to chemical probes
Time-resolved fluorescence	±	−	+
Multi-colour fluorescence	±	−	+	For FPs, multi-cloning and expression is necessary
In vitro applications	±	±	+
Variety of chemical group labelling	−	−	+
Pulse-chase analysis	−	−	+	Fresh synthetized FPs cannot be efficiently quenched
Anaerobic conditions	−	+	+	FPs’ fluorophore formation requires oxygen
Protein purification	+	+	+	Utilization of the GFP-trap matrix
Protein immobilization	+	+	+	Utilization of the GFP-trap matrix
Pull-down experiments	+	+	+	Utilization of the GFP-trap matrix

^a +, fully applicable or advantageous; ±, limited applicability; -, not applicable or disadvantageous; FPs = fluorescent proteins.