Cells can adapt to extracellular signal molecules in a variety of ways. Interestingly, exposure to a signal molecule can sometimes not only desensitize the cell to this molecule, but also to one or more other signal molecules that are recognized by different receptors, even if those receptors can still bind to their ligand at the cell surface and initiate signaling. Which subset of the following adaptation mechanisms (for the original signal) can in principle account for this type of desensitization? Choose all that apply. Your answer would be a string composed of letters A to E only, in alphabetical order; e.g. BDE.
(A) Receptor sequestration
(B) Receptor down-regulation
(C) Receptor inactivation
(D) Inactivity of signaling protein
(E) Production of inhibitory protein

Question

Cells can adapt to extracellular signal molecules in a variety of ways. Interestingly, exposure to a signal molecule can sometimes not only desensitize the cell to this molecule, but also to one or more other signal molecules that are recognized by different receptors, even if those receptors can still bind to their ligand at the cell surface and initiate signaling. Which subset of the following adaptation mechanisms (for the original signal) can in principle account for this type of desensitization? Choose all that apply. Your answer would be a string composed of letters A to E only, in alphabetical order; e.g. BDE.
(A)	Receptor sequestration
(B)	Receptor down-regulation
(C)	Receptor inactivation
(D)	Inactivity of signaling protein
(E)	Production of inhibitory protein

Quizplus · Accepted Answer

If the signaling pathways for the signals converge (or overlap), adaptation to one signal can also desensitize the cell to the others by affecting the common signaling molecules. In this example, convergence occurs downstream of the receptors; therefore, the first three mechanisms do not apply. Note that the first three adaptation mechanisms act on the receptor for the original signal, not on other receptors.

Cells Can Adapt to Extracellular Signal Molecules in a Variety