Green fluorescent protein TagGFP

- Fast protein maturation
- Bright green fluorescence
- Proven availability to generate stably transfected cell lines
- Monomeric protein with successful performance in fusions
- Recommended for protein labeling

TagGFP is an enhanced bright mutant of the Aequorea macrodactyla GFP-like protein [Xia et al., 2002]. TagGFP possesses bright green fluorescence with excitation/emission maxima at 482 and 505 nm, respectively. It is optimized for expression at 37oC. TagGFP is more pH-stable than EGFP. Because of monomeric nature, TagGFP is mainly intended for protein localization studies and expression in long-term cell cultures. It can also be used for cell labeling and gene expression analysis, although TurboGFP is preferable for such applications because it matures faster and gives brighter fluorescent signal.

Main properties

TagGFP normalized excitation (thin line) and emission (thick line) spectra. Download TagGFP 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 482 Emission maximum, nm 505 Quantum yield 0.59 Extinction coefficient, M-1cm-1 58 200 Brightness* 34.3 Brightness, % of EGFP 104 pKa 4.7 Structure monomer Aggregation no Maturation rate at 37°C fast Photostability high Cell toxicity not observed Main advantages bright green monomeric fluorescent protein

Recommended filter sets and antibodies

The protein can be recognized using Anti-Tag(CGY)FP antibody (Cat.# AB121-AB122) available from Evrogen.

TagGFP 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

TagGFP can be easily expressed and detected in a wide range of organisms. Mammalian cells transiently transfected with TagGFP expression vectors give bright fluorescent signals within 10-12 hrs after transfection. No cell toxic effects and visible protein aggregation are observed.

Being expressed in mammalian cells, TagGFP shows brightness and maturation speed similar to those of EGFP. However, compared with EGFP, TagGFP matures more than two times faster in E. coli cells.

TagGFP and EGFP expression in E. coli, 10 hrs after transformation

TagGFP 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 cyan, yellow, red, and far-red fluorescent dyes.

TagGFP expression in transiently transfected mammalian cells (A) Whole-cell expression; (B) TagGFP fusion with human β-actin; (c) TagGFP fusion with human α-tubulin. See also 3D movie of TagGFP-tagged tubulin

TagGFP suitability to generate stably transfected cells has been proven by Marinpharm company. Cell lines expressing TagGFP fusion with α-tubulin are commercially available from this company.

Stably transfected cell lines expressing TagGFP-tagged fusions (A) TagGFP-tagged α-tubulin in MDCK canine kidney epithelial cells; (B) TagGFP-tagged α-tubulin in T24 cells; (c) TagGFP fusion with human β-actin in U-205 human osteosarcoma cells. Images were kindly provided by Dr. Christian Petzelt (Marinpharm).

Available variants and fusions

TagGFP 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.

TagGFP-mito fusion: A mitochondrial targeting sequence (MTS) is linked to the TagGFP 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.

TagGFP-actin fusion: Human β-actin is linked to the TagGFP C-terminus. When expressed in mammalian cells, this fusion provides green fluorescent labeling of actin filaments.

TagGFP-tubulin fusion: Human α-tubulin is linked to the TagGFP C-terminus. When expressed in mammalian cells, this fusion provides green fluorescent labeling of tubulin filaments.