Red fluorescent protein JRed

- True-red fluorescence
- Proven suitability to create stably transfected cell lines

JRed is a red fluorescent protein obtained by mutagenesis of Anthomedusae jellyfish chromoprotein [Shagin et al., 2004]. JRed fluorescence (excitation/emission maxima are 584 and 610 nm, respectively) can be detected using most popular filter sets.

Main properties

JRed normalized excitation (thin line) and emission (thick line) spectra. Download JRed spectra (xls)

CHARACTERISTIC * Brightness is a product of extinction coefficient and quantum yield, divided by 1000. Molecular weight, kDa 27 Polypeptide length, aa 242 Fluorescence color true-red Excitation maximum, nm 584 Emission maximum, nm 610 Quantum yield 0.20 Extinction coefficient, M-1cm-1 44 000 Brightness* 8.8 Brightness, % of EGFP 26 pKa 5.0 Structure weak dimer Aggregation no Maturation rate at 37°C slow Photostability medium Cell toxicity at certain excitation wavelengths Main advantages true-red fluorescent protein with good compatibility with popular filter sets Possible limitations dimer, limited applicability for fusions generation; unsuitable for expression in procaryotes

Recommended filter sets and antibodies

JRed can be recognized using Anti-KillerRed antibody (Cat.# AB961) available from Evrogen.

JRed can be detected using TRITC filter set or similar. Recommended Omega Optical filter sets are QMAX-Red and XF174.

Performance and use

JRed can be expressed in eukaryotic cells; however, it is not appropriate for expression in prokaryotic.

JRed possesses relatively fast photobleaching rate upon arc lamp irradiation. At the same time, it exhibits high photostability when excited by 543 nm laser line in a confocal microscope, with the photobleaching time several times longer compared with DsRed2. JRed could show phototoxicity when bleached.

Mammalian cells transiently transfected with JRed vector give red fluorescence without visible aggregation. Mammalian cells transiently transfected with JRed expression vectors produce bright fluorescence in 24 hours after transfection.

JRed suitability to generate stably transfected cells has been proven by Marinpharm company.

Fluorescent microscopy of stably transfected mammalian cells expressing JRed in cytosol. Images were kindly provided by Dr. Christian Petzelt (Marinpharm).

Despite dimerization capacity, JRed demonstrates successful performance in fusions with subcellular localization signals and many cellular proteins including BH3 interacting domain death agonist (BID), nucleolar protein fibrillarin, dopamin transporter (hDAT). However, we recommend that you use monomeric TagFPs for protein labeling applications.

Fluorescent microscopy of mammalian cells expressing JRed fusions. Image of stably transfected PtK rat kangaroo cells expressing mitochondria-targeted JRed was kindly provided by Dr. Christian Petzelt (Marinpharm).