The binding of human growth hormone (hGH) to the human growth hormone receptor (hGHR) is a key endocrinological process that controls critical aspects of cell growth, proliferation, and differentiation. Mechanistically, this sequential, asymmetric binding event involves the interaction between a single hGH molecule and distinct sites (sites 1 and 2) on the extracellular domain of a preformed hGHR homodimer. Our group recently identified S1H, a rationally designed peptide sequence mimetic of the