Intermolecular NH2-/Carboxyl-Terminal Interactions in Androgen Receptor Dimerization Revealed by Mutations That Cause Androgen Insensitivity

The study investigated the structural alignment of the human androgen receptor dimer by introducing mutations in the steroid binding domain that cause androgen insensitivity. It was found that most mutants maintained androgen binding affinity but had increased dissociation rates and required higher dihydrotestosterone concentrations for activation. A 2-hybrid protein interaction assay revealed that the steroid binding domain interacts with the NH2-terminal-DNA binding domain fragment and the full-length androgen receptor in a dose-dependent manner. Mutations at Val-889 and Arg-752 disrupted the NH2-/carboxyl-terminal interaction in the steroid binding domain fragment but not in the full-length receptor. The N-C interaction was shown to reduce androgen dissociation and slow degradation of the steroid binding domain fragment, suggesting that Val-889 and Arg-752 are critical for this interaction and that an intermolecular N-C interaction occurs during receptor dimerization, resulting in an antiparallel arrangement of androgen receptor monomers.