ANATOMY

Detailed explanation-1: -So, the correct answer is ‘Cyclic AMP’

Detailed explanation-2: -The second messenger is the mechanism of the action of hydrophilic hormones with receptors in the target cells. The receptors for hydrophilic hormones are present on the plasma membrane of the target cells. The first messengers interact with receptors on cell membranes which form the Hormone-Receptor Complex.

Detailed explanation-3: -cAMP is the prototypical second messenger and adenylyl cyclase (AC) its sole source. In cyanobacteria, cAMP levels respond rapidly to environmental changes, and in Anabaena cylindrica it has been shown to act as a second messenger of light signal transduction (5).

Detailed explanation-4: -cAMP and Ca2+ are two important second messengers, which mediate the intracellular effects of cell surface receptors (109). These two second messengers regulate a variety of cellular functions, including protein synthesis, protein phosphorylation, the regulation of enzymatic activity (110) and gene expression.