Final answer:
Extrajunctional receptors are found in the cell membrane of cells. Each cell-surface receptor has an extracellular domain responsible for binding to ligand molecules outside the cell.
Step-by-step explanation:
Extrajunctional receptors are found in the cell membrane of cells.
Each cell-surface receptor has three main components: an external ligand-binding domain called the extracellular domain, a hydrophobic membrane-spanning region called a transmembrane domain, and an intracellular domain inside the cell. The size and extent of each of these domains vary widely, depending on the type of receptor.
The extracellular domain of a receptor is responsible for binding to ligand molecules outside the cell.