Lasofoxifene interaction with ERα is typical of those between SERM-ERα such as a nearly planar topology (the tetrahydronapthalene carbocycle), hydrogen bonding with Arg-394 and Glu-353 and the phenyl side chains of lasofoxifene filling the C-ring and D-ring volume of the ligand-binding pocket. Lasofoxifene diverts helix 12 and prevents the binding of coactivator proteins with LXXLL motives. This is achieved by lasofoxifene occupying the space normally filled by Leu-540's side group and modulating the conformation of residues of helix 11 (His-524, Leu-525). Furthermore, lasofoxifene also directly interferes with helix 12 positioning by the drug's ethyl pyrrolidine group. In vitro studies indicate that bazedoxifene competitively blocks 17β-estradiol by high and similar binding to both ERα and ERβ. Bazedoxifenes main binding domain consists of the 2-phenyl-3-methylindole and a hexamethylenamine ring at the side chain affected region.