AP BIOLOGY

Detailed explanation-1: -In the case of the epinephrine receptor, the G protein is a Gs, meaning that the subunit of the heterotrimeric G-protein stimulates adenylyl cyclase to increase the cytosolic concentration of cyclic AMP (3′, 5′cyclic adenosine monophosphate). The cAMP is the “second messenger” within the hepatocyte.

Detailed explanation-2: -When epinephrine binds to cells, it stays outside on the membrane‐bound receptor. The second messenger, cyclic AMP, is made by the enzyme adenylate cyclase.

Detailed explanation-3: -In muscle, glycogen phosphorylase is activated by hormones and neural signals such as epinephrine, that stimulate phosphorylase kinase which phosphorylates the Ser-14 residue of the protein.

Detailed explanation-4: -Glucagon and epinephrine can activate phosphorylase by causing a sequence of reactions (the cascade; Fig. 2) that results in the conversion of phosphorylase b to a. First, these hormones bind to their specific receptors.

Detailed explanation-5: -Abstract. Epinephrine increases glycogen synthase (GS) phosphorylation and decreases GS activity but also stimulates glycogen breakdown, and low glycogen content normally activates GS.