Table 1. Selected NIR FPs engineered from bacterial phytochromes with the demonstrated in vivo applications.

NIR FP	Ex, nm	Em, nm	Extinction coefficient, M−1 cm−1	Quantum yield, %	Molecular brightness versus iRFP713, %	Oligomeric state	Photostability in mammalian cells, t1/2, s	pKa	Brightness in HeLa cells versus iRFP713, %*	Ref.
miRFP670v1	644	670	71,300±2,100	11.6±0.5	134	Monomer	155±6	4.5	30.0±1.7	This work
miRFP670	642	670	87,400±2,600	14.0±0.6	198		155±5	4.5	72.0±3.5
miRFP703	674	703	90,900±2,700	8.6±0.5	127		394±7	4.5	37.4±2.4
miRFP709	683	709	78,400±2,400	5.4±0.2	69		192±5	4.5	30.1±1.9
mIFP†	683 (683)	705 (704)	65,900±2,000 (82,000)	6.9±0.9 (8.4)	74	Monomer	54±5	4.5	14.5±2.9	1717
IFP2.0†,‡	688 (690)	709 (711)	72,900±2,200 (98,000)	6.8±0.2 (8.1)	80	Dimer§	108±6	4.5	7.9±1.1	1818
iRFP670	643	670	114,000	12.2	225	Dimer	290	4.0	119	1616
iRFP682	663	682	90,000	11.1	162		490	4.5	105
iRFP702	673	702	93,000	8.2	124		630	4.5	61
iRFP713 (aka iRFP)	690	713	98,000	6.3	100		960	4.5	100	44
iRFP720	702	720	96,000	6.0	93		490	4.5	110	1616

FP, fluorescent proteins; NIR, near-infrared. Error, s.d. (n=3).

^*Determined as effective NIR fluorescence in transiently transfected live HeLa cells with no supply of exogenous BV and after normalization to fluorescence of co-transfected EGFP.

^†Characteristics of IFP1.4, IFP2.0 and mIFP from the original paper¹⁷ are shown in parentheses. Parameters determined in this paper are shown without parentheses.

^‡Only IFP2.0 is presented as the latest version in a series of the IFP proteins¹⁸.

^§Although IFP2.0 was originally reported as a monomer¹⁸, later it was found to be a dimer¹, which was also confirmed by its developers¹⁷.