Table 1. Characteristics of far-red fluorescent proteins.

Protein	Excitation peaka	Emission peaka	εb	φc	Brightness excited at peakd	Brightness excited at 633nme	Photostabilityf	pKa
dTomatog	554	581	69000	0.69	48	0	64	4.7
mCherryg	587	610	72000	0.22	16	0.084	68	<4.5
mPlumg	590	649	41000	0.10	4.1	0.26	53	<4.5
mRaspberryg	598	625	86000	0.15	13	0.45	15	<4.5
mGrape3	608	646	40000h	0.03	1.2	0.29	5	7.0
mKate	585	635	42000	0.30	13	0.43	82	6.2i
mKate S158A	585	630	75000	0.30	23	0.48	327	5.4i
mKate2	586	630	50000	0.36	18	0.42	ND	5.4i
mKate S158C	586	630	63000	0.33	21	0.56	220j	ND
mKate M41G S158C	593	648	73000	0.22	16	1.2	ND	ND
Neptune (mKate M41G S61C S158C Y197F)	600	650	72000	0.18	13	1.7	185	5.8
mNeptune (Neptune M146T)	600	650	67000	0.20	13	1.8	160	5.4

^aExcitation and emission maxima in nm.

^bMaximum extinction coefficient per chain in M^-1cm^-1 measured by the alkali denaturation method (Chalfie and Kain, 2005; Gross et al., 2000).

^cQuantum yield of fluorescence.

^dCalculated as (peak extinction coefficient per chain • quantum yield)/(1000 M^-1cm^-1).

^eCalculated as (extinction coefficient per chain at 633 nm • quantum yield • emission fraction above 633 nm)/(1000 M^-1cm^-1).

^fTime in s to photobleach 50% from an initial rate of 1000 emitted photons s^-1 molecule^-1.

^gPublished values for dTomato, mCherry, and mPlum (Shaner et al., 2005).

^hAfter photoactivation by 470nm light.

ⁱPublished values (Pletnev et al., 2008).

^jMonoexponential decay.