Live-cell targeting of His-tagged proteins by multivalent N-nitrilotriacetic acid carrier complexes.

The selective and fast labeling of proteins in living cells is a major challenge. Live-cell labeling techniques require a high specificity, high labeling density, and cell permeability of the tagging molecule to target the protein of interest. Here, we report on the site-specific, rapid and efficient labeling of endogenous and recombinant histidine-tagged proteins at distinct subcellular compartments using cell-penetrating multivalent chelator carrier complexes. In vivo labeling was followed in real-time in living cells, demonstrating a high specificity and high degree of colocalization in the crowded cellular environment