> ## Documentation Index
> Fetch the complete documentation index at: https://docs.adaptyvbio.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Natural Ligands

> Endogenous peptides, proteins, or small molecules that bind biological targets

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.

<CardGroup cols={2}>
  <Card title="Types" icon="layers">
    Peptides, proteins, lipids, metabolites, nucleic acids
  </Card>

  <Card title="Affinity" icon="link">
    Native affinities tuned by evolution for function
  </Card>

  <Card title="Specificity" icon="target">
    High; often context- and isoform-dependent
  </Card>

  <Card title="Source" icon="leaf">
    Endogenous or purified from natural sources
  </Card>
</CardGroup>

## Key Concepts

<Tip>
  Studying native ligand–receptor pairs informs mechanism and guides therapeutic mimicry or antagonism.
</Tip>

* **Orthosteric vs. allosteric** interactions modulate signaling differently
* **Kinetics** (on/off rates) can be as important as affinity
* **Post-translational modifications** influence binding and function

<Warning>
  Natural heterogeneity and context-dependent behavior can complicate standardization and reproducibility.
</Warning>

## Applications

<AccordionGroup>
  <Accordion title="Mechanistic Studies">
    Map signaling pathways and validate targets using native binders.
  </Accordion>

  <Accordion title="Therapeutic Templates">
    Design peptide/protein mimetics or inhibitors based on native interactions.
  </Accordion>

  <Accordion title="Diagnostics">
    Use natural ligands as capture agents or biomarkers in assays.
  </Accordion>
</AccordionGroup>

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