I want to put a tag at either end of a gene of interest, and then express this gene in Mouse T cells. Finally, I want to recover the expressed fusion protein with the monoclonal antibody against this tag. I do not want my fusion protein to be contaminated with other proteins from T cells (I mean the monoclonal antibody has negligible cross reactivity with other proteins from T cells). Which tag is the best for this purpose? Please help me make this decision? Thanks.