Which ion-channel class is regulated by second messengers such as cAMP or Ca2+?

Which ion-channel class is regulated by second messengers such as cAMP or Ca2+?

• A. G-protein coupled receptors
• B. Second messenger regulated ion channels
• C. Voltage-gated ion channels
• D. Ligand-gated ion channels

Answer: (B)

Second messengers inside the cell can control how a channel behaves, linking signaling cascades to changes in electrical activity. When a signal outside the cell activates a receptor, it often ramps up or down levels of messengers like cyclic AMP or calcium. These messengers then modulate ion channels either by direct interaction or by activating kinases (like PKA) that phosphorylate the channel, changing how often it opens. Calcium can also bind directly to the channel or to calmodulin associated with the channel to adjust its activity. This makes the channel’s opening depend on intracellular signaling rather than just membrane voltage or direct ligand binding to the channel itself. That’s why the correct class is the second messenger–regulated ion channels. In contrast, voltage-gated channels respond to changes in membrane potential, and ligand-gated channels respond to a ligand binding directly to the channel. GPCRs are receptors that create the second-messenger signals, but they are not themselves the ion-channel class.

Second messengers inside the cell can control how a channel behaves, linking signaling cascades to changes in electrical activity. When a signal outside the cell activates a receptor, it often ramps up or down levels of messengers like cyclic AMP or calcium. These messengers then modulate ion channels either by direct interaction or by activating kinases (like PKA) that phosphorylate the channel, changing how often it opens. Calcium can also bind directly to the channel or to calmodulin associated with the channel to adjust its activity. This makes the channel’s opening depend on intracellular signaling rather than just membrane voltage or direct ligand binding to the channel itself.

That’s why the correct class is the second messenger–regulated ion channels. In contrast, voltage-gated channels respond to changes in membrane potential, and ligand-gated channels respond to a ligand binding directly to the channel. GPCRs are receptors that create the second-messenger signals, but they are not themselves the ion-channel class.