Which term describes the removal and storage of receptors away from the cell surface, reducing receptor availability?

Which term describes the removal and storage of receptors away from the cell surface, reducing receptor availability?

• A. Up-regulation
• B. Desensitization
• C. Sequestration/down-regulation
• D. Tachyphylaxis

Answer: (C)

Removing receptors from the cell surface and storing them inside the cell reduces how many receptors are available to bind ligand. This process is sequestration, often described as down-regulation, because the number of functional receptors on the membrane declines. Receptors are internalized into intracellular compartments, and then cells may recycle them back to the surface or target them for degradation. If receptors are fewer on the surface, signaling in response to a ligand diminishes. In contrast, up-regulation means more receptors appear on the surface; desensitization refers to a diminished response that can occur through functional uncoupling of the receptor from its signaling pathway (not necessarily a loss of surface receptors), and tachyphylaxis is a rapid form of such desensitization after repeated exposure.

Removing receptors from the cell surface and storing them inside the cell reduces how many receptors are available to bind ligand. This process is sequestration, often described as down-regulation, because the number of functional receptors on the membrane declines. Receptors are internalized into intracellular compartments, and then cells may recycle them back to the surface or target them for degradation. If receptors are fewer on the surface, signaling in response to a ligand diminishes.

In contrast, up-regulation means more receptors appear on the surface; desensitization refers to a diminished response that can occur through functional uncoupling of the receptor from its signaling pathway (not necessarily a loss of surface receptors), and tachyphylaxis is a rapid form of such desensitization after repeated exposure.