Bifunctional molecules and methods for their use in the production of binary complexes in a host are provided. The bifunctional molecule is a conjugate of a drug moiety and a presenter protein ligand. In the subject methods, an effective amount of the bifunctional molecule is administered to the host. The bifunctional molecule binds to the presenter protein to produce a binary complex that exhibits at least one of improved affinity, specificity or selectivity as compared to the corresponding free drug. The subject methods and compositions find use in a variety of therapeutic applications.