Which molecule is activated by cAMP in the epinephrine signaling pathway?

In the epinephrine signaling pathway, the molecule that is activated by cyclic adenosine monophosphate (cAMP) is protein kinase A (PKA). When epinephrine binds to its receptor, it initiates a signaling cascade that results in the production of cAMP from ATP by adenylate cyclase.

Once produced, cAMP serves as a secondary messenger and binds to the regulatory subunits of PKA. This binding causes the regulatory subunits to release from the catalytic subunits of PKA, thereby activating the kinase. The activated PKA can then phosphorylate various target proteins, leading to a range of cellular responses such as increased glucose release from glycogen and enhanced heart muscle contraction.

This mechanism highlights the crucial role of cAMP as a signaling molecule in mediating the effects of hormones like epinephrine, with PKA being a key effector in this process. Understanding this activation and subsequent signaling helps elucidate how cells respond to external signals and regulate metabolic processes accordingly.