Protein-trap version 2.1: screening for expressed proteins in mammalian cells based on their localizations.

BACKGROUND: "Protein-trap" is a method that allows epitope-tagging of endogenous proteins. This method allows for the identification of endogenously expressed proteins that exhibit specific localization of interest. This method has been recently reported for its application in the study of Drosophila development by using a relatively large epitope, green-fluorescent-protein (GFP). RESULT: Herein, we report a new "protein-trap" vector for mammalian cells. This new method utilizes a much smaller epitope-tag and also allows for drug-selection prior to the epitope-tagging. Pre-selection by drug resulted in the highly efficient protein-trapping frequency. CONCLUSION: The "protein-trap" method based on this new vector is expected to serve as a complimentary approach to the previously reported GFP-based method.