Which of the following statements best describes the role of adenylyl cyclase in the epinephrine signaling pathway?
A. It converts a polymer to its monomer subunits.
B. It moves substances across the plasma membrane.
ect!
C. It accelerates the production of a second messenger.
D. It transfers phosphate groups from to protein substrates.

C.It accelerates the production of a second messenger.

Explanation:

Adenylyl cyclase is an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP), a second messenger that activates the protein kinase A (PK-A) protein by dissociation of its regulatory subunit from the catalytic subunit. The first step of the epinephrine signaling pathway consists of the hormone binding to the epinephrine receptor localized on the cell surface. This binding activates a G protein inside the cell, which in turn activates the adenylyl cyclase enzyme. Subsequently, adenylyl cyclase converts ATP molecules into cAMP molecules. Since cAMP transports the message of the epinephrine hormone within the cell this molecule (cAMP) is considered to be a second messenger. Finally, cAMP activates the PK-A enzyme which phosphorylates different proteins and thus triggers different biological processes.