Chemical inducers of dimerization: The atomic structure of FKBP12-FK1012A-FKBP12

A ligand that simultaneously binds two proteins must have two high affinity protein binding domains joined in a fashion that facilitates, or at least does not prevent, protein-protein interaction. Designing such ligands is challenging, and a high resolution X-ray structure of FKBP12-FK1012A-FKBP12 illustrates the subtleties of one successful design.