Figure 1From: Distribution patterns of small-molecule ligands in the protein universe and implications for origin of life and drug discoveryPower-law behaviors of ligand-protein binding. The number of ligands (N) decays with an increase in the number (L) of (a) domains and (b) folds that bind the ligand and follows the equation N = aL-b. The figure illustrates that a few ligands cover tens of protein domains or folds, while most ligands bind only one domain or fold.Back to article page