Ligand

Definition

A ligand is a molecule that binds to a specific site on a target protein, often a receptor, to induce a biological response. Ligands can be endogenous (originating within the body) or exogenous (originating outside the body, such as drugs).

5 Must Know Facts For Your Next Test

1. Ligands interact with receptors through specific binding sites, leading to changes in cellular activity.
2. The strength of the interaction between a ligand and its receptor is measured by affinity.
3. Agonists are ligands that activate receptors, while antagonists block receptor activity.
4. Ligand-receptor interactions are crucial for understanding drug mechanisms and therapeutic effects.
5. The concept of selectivity refers to a ligand's ability to bind to one type of receptor over others.

Review Questions

• What role do ligands play in receptor activation?
• How does an agonist differ from an antagonist?
• Why is affinity important in the context of ligand-receptor interactions?

Related terms

Receptor: A protein molecule that receives and responds to a ligand.

Agonist: A type of ligand that binds to a receptor and activates it to produce a biological response.

Antagonist: A type of ligand that binds to a receptor but does not activate it; instead, it blocks or dampens the action of agonists.