Question

amino acid hormones
what often serves as the second messenger when a hydrophilic amino acid - based hormone binds its receptor?
adenylate cyclase
guanine nucleotide - binding protein (g protein)
protein kinase
cyclic adenosine monophosphate (camp)

Explanation:

Hydrophilic amino acid - based hormones cannot pass through the cell membrane. They bind to cell - surface receptors. Adenylate cyclase is an enzyme, G protein is involved in signal transduction but is not the second messenger. Protein kinase is an enzyme that phosphorylates proteins. Cyclic adenosine monophosphate (cAMP) is a common second messenger in the signaling pathway of hydrophilic hormones. When a hydrophilic amino acid - based hormone binds its receptor, it often activates a G protein, which in turn activates adenylate cyclase. Adenylate cyclase converts ATP to cAMP, and cAMP then acts as the second messenger to carry out the intracellular signaling.

Answer:

Cyclic adenosine monophosphate (cAMP)