The technology described herein is directed to inducible and repressible polypeptides and polypeptide systems. In particular, described herein are split sequence-specific nucleases and split recombinases that are linked to drug-inducible or drug-repressible dimerization domains. In some embodiments, the polypeptides comprise sequestering domains and/or have their expression controlled by an inducible promoter. In multiple aspects described herein are polynucleotides, vectors, cells, and pharmaceutical compositions comprising said polypeptides or polypeptide systems. Also described herein are methods of using said polypeptide systems to modulate the expression of a target polypeptide or to treat a subject in need of a cell therapy.