Natural ligands are endogenous molecules—peptides, proteins, lipids, nucleic acids, or small molecules—that bind specifically to receptors, enzymes, or other macromolecules to elicit biological effects.

Types

Peptides, proteins, lipids, metabolites, nucleic acids

Affinity

Native affinities tuned by evolution for function

Specificity

High; often context- and isoform-dependent

Source

Endogenous or purified from natural sources

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Key Concepts

Studying native ligand–receptor pairs informs mechanism and guides therapeutic mimicry or antagonism.
  • Orthosteric vs. allosteric interactions modulate signaling differently
  • Kinetics (on/off rates) can be as important as affinity
  • Post-translational modifications influence binding and function
Natural heterogeneity and context-dependent behavior can complicate standardization and reproducibility.

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Applications

Where relevant, see related formats: peptides, miniproteins, and antibody-derived formats (IgG, Fab, scFv, VHH).