ligand-binding domain

The ligand-binding domain is a specific part of a protein, often a receptor, that recognizes and attaches to a chemical messenger called a ligand, such as a hormone or drug. This domain has a unique shape and structure that matches the ligand, allowing the protein to detect its presence. When the ligand binds, it can trigger a change in the protein's activity or shape, leading to a biological response. Think of it as a lock-and-key system, where the ligand is the key that fits into the ligand-binding domain, enabling the protein to perform its function.