Green fluorescent protein TagGFP2

- Bright green fluorescence
- Monomeric protein with successful performance in fusions
- Fast maturation, high pH-stability and photostability
- Proven suitability to generate stably transfected cell lines
- Recommended for protein labeling and FRET applications

TagGFP2 (scientific name mTagGFP) is the improved variant of TagGFP, the mutant of the Aequorea macrodactyla GFP-like protein [Xia et al., 2002, Subach et al., 2008]. TagGFP2 possesses bright green fluorescence with excitation/emission maxima at 483 and 506 nm, respectively. TagGFP2 matures 1.6-fold faster than TagGFP and is characterized by the improved performance in fusions. Compared to EGFP, TagGFP2 provides about the same brightness of fluorescence but is significantly more pH stable. TagGFP2 is specially optimized for expression at 37°C. Because of monomeric nature, TagGFP2 is mainly intended for protein localization studies and expression in long-term cell cultures. In FRET applications, TagGFP2 can be used as a donor for red fluorescent protein TagRFP or as an acceptor for blue fluorescent protein TagBFP.

Main properties

TagGFP2 normalized excitation (thin line) and emission (thick line) spectra. Spectra viewer tool Download TagGFP2 spectra (xls)

CHARACTERISTIC * Brightness is a product of extinction coefficient and quantum yield, divided by 1000. Molecular weight, kDa 27 Polypeptide length, aa 238 Fluorescence color green Excitation maximum, nm 483 Emission maximum, nm 506 Quantum yield 0.6 Extinction coefficient, M-1cm-1 56 500 Brightness* 33.9 Brightness, % of EGFP 105 Fluorescence lifetime, ps 3200 Fluorescence intensity decay nearly single-exponential pKa 5.0 Structure monomer Aggregation no Maturation rate at 37°C fast Photostability high Cell toxicity not observed Main advantages bright green monomeric fluorescent protein

Maturation curves for TagGFP2 and parental TagGFP. Dashed lines indicate maturation half-times of 11 min and 18 min for TagGFP2 (dark green curve) and TagGFP (light green curve), respectively. Recording of protein maturation was started when about 7% from their maximal fluorescence has been detected. Time point "0" was defined using an approximation of the beginning of the maturation curves with straight lines. Data from Subach et al., 2008.

Recommended filter sets and antibodies

The protein can be recognized using Anti-Tag(CGY)FP antibody (Cat.# AB121) or Anti-GFP antibody (Cat.# AB011) available from Evrogen.

TagGFP2 can be detected using common fluorescence filter sets for EGFP, FITC, and other green dyes. Recommended Omega Optical filter sets are QMAX-Green, XF100-2, XF100-3, XF115-2, and XF116-2.

Performance and use

TagGFP2 can be easily expressed and detected in a wide range of organisms. Mammalian cells transiently transfected with TagGFP2 expression vectors produce bright fluorescence in 10-12 hrs after transfection. No cytotoxic effects or visible protein aggregation are observed.

TagGFP2 performance in fusions has been demonstrated in the β-actin, α-tubulin and mitochondria-targeting signal models. It can be used in multicolor labeling applications with blue, true-yellow, red, and far-red fluorescent dyes.

	TagGFP2 expression in transiently transfected mammalian cells.

Available variants and fusions

Variant	Description	Related vector	Cat.#	Click for image
Humanized TagGFP2	TagGFP2 codon usage is optimized for high expression in mammalian cells [Haas et al., 1996], but it can be successfully expressed in many other heterological systems.	pTagGFP2-C	FP191
		pTagGFP2-N	FP192
TagGFP2-actin fusion	Human β-actin is fused to the TagGFP2 C-terminus. When expressed in mammalian cells, this fusion provides green fluorescent labeling of β-actin in living cells.	pTagGFP2-actin	FP194
TagGFP2-tubulin fusion	Human α-tubulin is fused to the TagGFP2 C-terminus. When expressed in mammalian cells, this fusion provides green fluorescent labeling of α-tubulin in living cells.	pTagGFP2-tubulin	FP195
TagGFP2-mito fusion	A mitochondrial targeting sequence (MTS) is fused to the TagGFP2 N-terminus. MTS was derived from the subunit VIII of human cytochrome C oxidase [Rizzuto et al., 1989; Rizzuto et al., 1995]. When expressed in mammalian cells, this variant provides green fluorescent labeling of mitochondria.	pTagGFP2-mito	FP197