27. Which of the following statements regarding G protein or G protein-mediated signal transduction is incotrect?
(1) Epinephrine binding to the beta-adrenergic receptor causes an activation of adenylyI cyclase through the activation of a stimulatory G protein.
(2) Gi alpha submit of the trimeric G proteins can inhibit adenylyl cyclase
(3) Gq alpha submit of the trimeric G proteins can stimulate Pl-phospholipase C
(A) I and 2
(B) I and 3
(C) 2 and 3
(D) all of the above.
(E) none of the above.