Consider following two compounds – estradiol and raloxifene - that interact with estrogen receptor, a
GPCR (see the figure below - binding site residues and interactions are depicted in blue). Note that
estradiol is an agonist, whereas raloxifene acts as an antagonist of estrogen receptor. Explain why
Tamoxifen and its metabolite can, therefore, act as an antagonist and agonist of the same estrogen
receptor, respectively.