Question

In the mechanism of action of a protein hormone, one of the second messengers is?

• A. Cyclic AMP
• B. Insulin
• C. $T_3$
• D. Gastrin

Answer 1

The correct option is A Cyclic AMP

In the mechanism of action of a protein hormone like Glucagon, Calcitonin etc, cAMP is the second messenger. A second messenger is present in the cytoplasmic or intracellular region and triggers a cascade of reactions when signaled by the first messenger or the hormone.

The cell membrane of the target cells have certain extracellular or exposed receptors that allow the binding of the first messenger or the hormone this in turn triggers the second messenger to activate a series of physiological changes within the cell.

Insulin, $T_3$ and Gastrin are hormones or first messengers.

So, the correct answer is 'Cyclic AMP'