What is a common tag used alongside GFP for dual-labeling experiments?

In dual-labeling experiments, it’s common to use fluorescent proteins that emit at distinct wavelengths to differentiate them visually. RFP, or Red Fluorescent Protein, is an effective partner for GFP because it emits red light while GFP emits green light. This spectral distinction allows researchers to observe the two proteins simultaneously using fluorescence microscopy without interference.

Using RFP helps to enhance the contrast in imaging experiments, allowing for clearer visualization of cellular processes or interactions between the proteins. By utilizing both GFP and RFP, scientists can effectively monitor co-localization and interactions in live cells, making it a popular choice for such experiments.

Other fluorescent proteins like CFP, YFP, and BFP also serve similar roles but have different characteristics that may make them less effective in certain experimental contexts. The pairing of colors must provide sufficient spectral separation to avoid overlap in emission, and red emissions can be distinctly observed from green emissions, making RFP a preferred option when dual-labeling with GFP.