Selectivity · fingerprint
α-MSH binds MC1R most tightly of the five melanocortin receptors — about 4.0 nM — and prefers it over MC3R by roughly 1.6×, 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: α-MSH 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 α-MSH 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.