Figure 5.

The endogenous ligand resource offers browsing across both multiple ligand and receptors. Four sections present (i) receptors (names and classification), (ii) endogenous ligands (name with link to detailed ligand info, ligand type (small molecule, peptide, protein), classification into principal, secondary or none categories, and potency rank), (iii) bioactivities (pEC₅₀ and pK_i minimum, average, and maximum values across studies) and (iv) references (publication link). All endogenous ligands and their primary/secondary classification were derived from the Guide to Pharmacology database (15).