Question

Which of the following is a second messenger?

• A. Sodium
• B. Cyclic AMP
• C. IP3
• D. Both b and c

Answer 1

The correct option is D Both b and c

Water soluble hormones, which include amino-acid derivatives, peptides, polypeptides, and proteins, interact with membrane-bound receptors, since they cannot cross the cell membrane and enter the cell. So, to produce their effects, they generate second messengers inside the cell, which in turn regulate cellular metabolism.
These second messengers include cyclic adenosine monophosphate (cyclic AMP ), inositol-1,4,5-triphosphate $I{P}_3$, and calcium ions.
Sodium is not a second messenger.

So, the correct answer is option 'd'.