Abstract: Methods and compositions related to a nucleic acid-guided nuclease cell targeting screen are provided. The invention relates to compositions and methods for identifying cell targeting proteins that, when associated with a nucleic acid-guided nuclease (such as Cas9), enables at least the nucleic acid-guided nuclease to be targeted to the surface of a target cell or internalized by a target cell, i.e., a cell targeted by the cell targeting agent.

Abstract: Methods and compositions related to intracellular delivery of gene editing proteins are provided. The invention relates to compositions and methods for transporting gene editing polypeptides, such as Cas9 or Cas12, into a cell ex vivo or in vivo. The invention includes a targeted active gene editing (TAGE) agent that includes an extracellular cell membrane binding moiety, e.g., an antigen binding polypeptide, a cell penetrating peptide (CPP), a ligand, or combinations thereof, that specifically binds to an extracellular cell membrane-bound molecule (e.g., a cell surface molecule), and a site-directed modifying polypeptide that recognizes a nucleic acid sequence. The extracellular cell membrane binding moiety (e.g.