ligand
Definition
A ligand is a molecule that binds to a specific site on a target protein or receptor, forming a complex that triggers a biological response. Ligands can be endogenous (naturally occurring in the body, such as hormones, neurotransmitters, or growth factors) or exogenous (external molecules like drugs or toxins). The interaction is typically reversible and governed by binding affinity and specificity. Ligand binding induces conformational changes in the target protein, initiating downstream signaling cascades or modulating protein activity. Understanding ligand-receptor interactions is fundamental to drug discovery, as most therapeutic agents function as ligands that either activate (agonists) or block (antagonists) specific receptors to achieve desired pharmacological effects.
Visualize ligand in Nodes Bio
Researchers can map ligand-receptor networks to visualize binding interactions, downstream signaling pathways, and off-target effects. Network graphs reveal how a single ligand may interact with multiple receptors, or how different ligands compete for the same binding site. This visualization helps identify potential drug candidates, predict side effects, and understand polypharmacology patterns across disease contexts.
Visualization Ideas:
- Ligand-receptor binding networks showing selectivity and promiscuity patterns
- Drug-target interaction maps with polypharmacology connections
- Signaling cascade networks initiated by ligand binding events
Example Use Case
A pharmaceutical team developing a new cancer therapeutic investigates how their small molecule ligand binds to multiple receptor tyrosine kinases (RTKs). By mapping the ligand's interactions across the kinome, they discover unexpected binding to VEGFR2, suggesting potential anti-angiogenic properties. Network analysis reveals that this off-target interaction connects to pathways involved in tumor vascularization, leading them to reposition the compound as a dual-action therapy targeting both tumor growth and blood vessel formation.