Antibody-Linked Fluorogen-Activating Proteins for Antigen Detection and Cell Ablation

We demonstrate selective labeling of cell surface proteins using fluorogen-activating proteins (FAPs) conjugated to standard immunoglobulins (IgGs). Conjugation was achieved with a polypeptide reagent comprised of an N-terminal photoactivatable Fc-binding domain and a C-terminal FAP domain. The resulting FAP–antibody conjugates were effective agents for protein detection and cell ablation in cultured mammalian cells and for visualizing cell–cell contacts using a tethered fluorogen assay. Because our approach allows FAP–antibody conjugates to be generated for most currently available IgGs, it should have broad utility for experimental and therapeutic applications