THIQ is the first selective agonist of the melanocortin-4 receptor (MC4R), with high affinity and potency for hMC4R (IC50=1.2 nM, EC50=2.1 nM) and rMC4R (IC50=0.6 nM, EC50=2.9 nM). THIQ maintains low potency at MC1R, MC3R and MC5R. THIQ plays a role in eliciting erectile activity in rodents. THIQ acts as a pharmacoperone of the MC4R rescuing the cell surface expression and signaling of some intracellularly retained MC4R mutants.