mRuby2

mRuby2 is a basic (constitutively fluorescent) red fluorescent protein published in 2012, derived from Entacmaea quadricolor. It has moderate acid sensitivity.

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Oligomerization	Organism	Molecular Weight	Cofactor
Monomer	Entacmaea quadricolor	26.5 kDa	-

FPbase ID: 8MJ78

Attributes

Ex λ	Em λ	EC (M^-1 cm^-1)	QY	Brightness	pKa	Maturation (min)	Lifetime (ns)
559	600	113,000	0.38	42.94	5.3	150.0	2.5

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mRuby2 OSER Measurements

% Normal Cells	OSER/NE ratio	Cell Type	Reference
87.4 ± 5.8 (10000 cells)	-	HeLa	Cranfill et al. (2016)
33.3 (60 cells)	-	HeLa	Costantini et al. (2015)
14.0 (113 cells)	-	U-2 OS	Bindels et al. (2016)
87.4 ± 5.8 (10000 cells)	-	HeLa	Shaner et al. (2013)

Photostability

t_1/2 (s)	Power	Light	Mode	In Cell	Fusion	˚C	Reference
123.0							Bindels et al. (2016)

A caution on interpretation of photostability measurements

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mRuby2 Sequence

mRuby2 was derived from mRuby with the following mutations: N2_S3delinsVSKGEE/L15M/I102V/A119V/A131P/*228MextDELYKN2_S3delinsVSKGEE/L15M/I102V/A119V/A131P/*230MextDELYK
amino acid numbers relative to mRubyeqFP611. show relative to eqFP611 show relative to mRuby

MVSKGEELIKENMRMKVVMEGSVNGHQFKCTGEGEGNPYMGTQTMRIKVIEGGPLPFAFDILATSFMYGSRTFIKYPKGIPDFFKQSFPEGFTWERVTRYEDGGVVTVMQDTSLEDGCLVYHVQVRGVNFPSNGPVMQKKTKGWEPNTEMMYPADGGLRGYTHMALKVDGGGHLSCSFVTTYRSKKTVGNIKMPGIHAVDHRLERLEESDNEMFVVQREHAVAKFAGLGGGMDELYK

GenBank: AFR60232

IPG: 30275455

Excerpts

Negligible photochromic behavior was measured for the mScarlet variants, while TagRFP-T, mRuby2, mRuby3 and mApple showed 15%, 19%, 41%, and 51% photochromic behavior, respectively. Hence, extreme care must be taken when using the latter four RFP variants as acceptors in FRET studies, since a photochromic effect is easily confused with a changed FRET state, especially if one considers that the typical FRET contrast in many sensors is in the range of only 5–20%. The photochromic behavior can also interfere with characterization of FPs, like determination of photostability (Supplementary Fig. 8) or brightness (Supplementary Fig. 5l).

Bindels et al. (2016)