90Which description about β-adrenergic pathway (a G-protein coupling receptor; GPCR) is not correct?
(A) The receptor is a 7-transmembrane protein.
(B) Epinephrine binds to a GPCR.
(C) The occupied receptor could cause the replacement of the GDP bound to GS (stimulatory G protein) by GTP,activating GS.
(D) GSβ moves to adenylyl cyclase and activates it to synthesize cAMP.
(E) cAMP activates PKA to trigger cellular response.