Hi Sehar,

In case you want to label your recombinant Protein with Red Dye:

1- Depending on what kind of reaction you want, you can either use a maleimide red dye which will target cysteine in your protein or an NHS-Ester red dye which will target basic amino acid on your protein such as lysine... 

2- you will need to use a maximum Dye/protein molar ratio of 2 to 4 in your reaction to avoid self Fluorescence quenching of your dyes...

3- incubate your dye-protein solution for 1 to 2 hours in a phosphate-sodium buffer PH-8.5 at room temperature in darkness with gentle mixing (every 10-15 min)

4-Unbound dye then removed by several spin-separation cycles at 14,000 g using  Amicon ultra centrifugal filter with the right kDa cutoff for your protein followed with additional purification by size exclusion using a Sephadex G25 PD-10 gel filtration column for example...

Or for your detection you can use a Tagged-rAGR2 and detect your protein with anti tag fluorescent antibody !!

Hope this will help you.

Thank you Foued! this is quite helpful. Is this type of labeling suitable for Immunofluorescence or flow cytometry? If i go for  commercial protein labeling kit what type you would recommend? 

ThermoFisher/Invitrogen, Sigma and many other companies have protein labelling kits. The one from Molecular probes gives you flexibility to choose a specific dye from a range of excitation wavelengths for tagging and these are very good and tested for immunofluorescence.

Good Luck!

Hy Sehar

I agree with Zeeshan.. Kit from Molecular Probes or Thermo Fisher works very well and easy to use... U can target your protein with IF or cytometry.. I will sugest an ICC (imuno cytochemestry..)... With collocalisation of your labled protein with a cell membrane specific marker..Good luck

I already checked these kits. Thank you so much!

Hello, I'm reviving this old post since I'm dealing with a similar situation. I have a recombinant protein with 10xHis tag on the N' terminal and a Myc tag on the C' terminal. The protein is molecular weight is ~42.4 kDa. I would like to use the protein for analyzing antigen-specific memory B cells. I have in mind staining the protein with a fluorophore-conjugated anti-Myc or anti-His, and then using the labeled protein to stain the B cells population, followed by Flow cytometry analysis. Does anybody have an experience with such a procedure aimed at B cells? I am aware of the alternative of using the Molecular probes kits, but the first methods seems cheaper and more straightforward. Thank you!