Second messengers
A)can synthesize cAMP from AMP and ADP.
B)are intracellular kinases which lead to a cellular response.
C)are intracellular non-protein signalling molecules.
D)are signalling molecules which bind directly to the G-protein coupled receptor.

Question

Quizplus · Accepted Answer

Second messengers are intracellular non-protein signalling molecules that mediate the intracellular response of cells to external signals. Examples of second messengers include cAMP, cGMP, IP3, and DAG.

Answer: D
 Signalling molecules that bind directly to G-protein coupled receptors are called ligands or agonists. They do not fall under the category of second messengers, which are intracellular signalling molecules.

Second Messengers