YPet

YPet is a basic (constitutively fluorescent) yellow fluorescent protein published in 2005, derived from Aequorea victoria. It has moderate acid sensitivity.

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Oligomerization	Organism	Molecular Weight	Cofactor
Weak dimer	Aequorea victoria	26.9 kDa	-

FPbase ID: AQACH

Attributes

Ex λ	Em λ	EC (M^-1 cm^-1)	QY	Brightness	pKa	Maturation (min)	Lifetime (ns)
517	530	104,000	0.77	80.08	5.63

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YPet OSER Measurements

% Normal Cells	OSER/NE ratio	Cell Type	Reference
62.5 ± 5.2 (10000 cells)	-	HeLa	Cranfill et al. (2016)

Photostability

t_1/2 (s)	Power	Light	Mode	In Cell	Fusion	˚C	Reference
30.3	20.0 (mW/mm2)	LED	Widefield	Saccharomyces cerevisiae		24.0	Lee et al. (2020)
58.0	20.0 (mW/mm2)	LED	Widefield	HEK239A		24.0	Lee et al. (2020)

A caution on interpretation of photostability measurements

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YPet Sequence

BLAST

YPet was derived from Venus with the following mutations: I48L/L69V/S209F/V225L/L232E/D235NI47L/L68V/S208F/V224L/L231E/D234N
amino acid numbers relative to VenusavGFP. show relative to avGFP show relative to Venus

MVSKGEELFTGVVPILVELDGDVNGHKFSVSGEGEGDATYGKLTLKLLCTTGKLPVPWPTLVTTLGYGVQCFARYPDHMKQHDFFKSAMPEGYVQERTIFFKDDGNYKTRAEVKFEGDTLVNRIELKGIDFKEDGNILGHKLEYNYNSHNVYITADKQKNGIKANFKIRHNIEDGGVQLADHYQQNTPIGDGPVLLPDNHYLSYQSALFKDPNEKRDHMVLLEFLTAAGITEGMNELYK

Excerpts

YFP3 possessed six mutations that resulted in an RRC almost fivefold greater than that of the parental pair. YFP3 also conferred a roughly threefold improvement in FRET relative to the fast-maturing Venus YFP. In an attempt to further enhance YFP3 brightness, the Venus mutations were combined with those of YFP3 to yield YFP for energy transfer (YPet). Though YFP3 exhibited slower folding relative to Venus, combining YFP3 and Venus mutations resulted in intermediate folding kinetics.

Nguyen & Daugherty (2005)

Nguyen and Daugherty (2005) reported the development of an improved FRET pair, YPet & CyPet, which had a sevenfold enhancement of the FRET signal. However, we discovered that most of the signal enhancement was due to enhanced dimerization of YPet to CyPet within the tethered construct, and was substantially reduced when we incorporated the monomerizing mutation previously developed to prevent the weak dimerization of GFP (Zacharias et al. 2002).

Ohashi et al. (2007)