Selectivity · fingerprint
Melanotan II binds MC1R most tightly of the five melanocortin receptors — about 0.40 nM — and prefers it over MC5R by roughly 2.5×, a broadly non-selective fingerprint.
broad agonist
Bars are sized by binding strength (p-value, on a fixed MC1R–MC5R scale);ᵐ marks a mouse value.
Effectively non-selective: Melanotan II grips several receptors within an order of magnitude of each other, so it is not a clean single-target molecule.
The selectivity window is the fold-gap between a ligand's tightest and second-tightest receptor — a compact measure of how cleanly it picks a target. One caveat it cannot capture: binding is not function. These bars show how tightly Melanotan II holds each receptor, not what the receptor then does downstream. To put this ligand next to the others, use the selectivity visualizer; for every value with its citation, the binding matrix.
Affinity values from the IUPHAR/BPS Guide to PHARMACOLOGY; the selectivity window is derived from them. Educational resource, not medical advice — see the editorial standards.