Which mechanisms are involved in desensitization?

Which mechanisms are involved in desensitization?

• A. Phosphorylation
• B. Internalization
• C. Alteration in synthesis rate
• D. All of the above

Answer: (D)

Desensitization involves both rapid and longer-term changes that lower a cell’s response to a stimulus. Phosphorylation of the receptor by kinases (such as GRKs and other kinases like PKA or PKC) quickly uncouples the receptor from its G protein, dampening signaling without removing the receptor from the surface. Internalization then reduces the number of receptors available at the cell surface, further blunting the response to continued stimulation. On a longer timescale, altering the synthesis rate of the receptor changes how many receptors are produced, contributing to sustained downregulation. Since desensitization can occur through these fast, intermediate, and long-term mechanisms, all of the listed processes participate, making all of the above the best answer.

Desensitization involves both rapid and longer-term changes that lower a cell’s response to a stimulus. Phosphorylation of the receptor by kinases (such as GRKs and other kinases like PKA or PKC) quickly uncouples the receptor from its G protein, dampening signaling without removing the receptor from the surface. Internalization then reduces the number of receptors available at the cell surface, further blunting the response to continued stimulation. On a longer timescale, altering the synthesis rate of the receptor changes how many receptors are produced, contributing to sustained downregulation. Since desensitization can occur through these fast, intermediate, and long-term mechanisms, all of the listed processes participate, making all of the above the best answer.