Final answer:
Cell-surface receptors contain membrane-spanning domains, intracellular domains, and extracellular domains.
Step-by-step explanation:
Membrane-spanning domains, intracellular domains, and extracellular domains are found in cell-surface receptors. Each cell-surface receptor has three main components: an external ligand-binding domain, also known as the extracellular domain, a hydrophobic membrane-spanning region, and an intracellular domain inside the cell. The size and extent of each domain vary depending on the type of receptor.