Campbell Biology 11th Edition by Lisa Urry,Michael Cain,Steven Wasserman,Peter Minorsky,Jane Reece

Exercise 11

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells
A) Enzymatic activity was proportional to the amount of calcium added to a cell-free extract.
B) Receptor studies indicated that epinephrine was a ligand.
C) Glycogen breakdown was observed only when epinephrine was administered to intact cells.
D) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined.