A novel, brilliantly red fluorescent protein, DsRed has become available recently opening up a wide variety of experimental opportunities for double labeling and fluorescence resonance electron transfer experiments in combination with green fluorescent protein (GFP). Unlike in the case of GFP, proteins tagged with DsRed were often found to aggregate within the cell. Here we report a simple method that allows rescuing the function of an oligomeric protein tagged with DsRed. We demonstrate the feasibility of this approach on the subunit proteins of an oligomeric membrane channel, gap junction connexins. Additionally, DsRed fluorescence was easily detected 12–16 h post transfection, much earlier than previously reported, and could readily be differentiated from co-expressed GFP. Thus, this approach can eliminate the major drawbacks of this highly attractive autofluorescent protein.
