Answer:
The protein phosphatase-1 dephosphorylates the residues of serine, which are phosphorylated by the protein kinase A. The cyclic-AMP inducible genes are stimulated by CREB that is phosphorylated by protein kinase A. Thus, overexpression of protein phosphatase 1 would prevent their induction.
Although, protein phosphatase 1 would not influence the function of cAMP-gated ligand channels, as these channels are opened directly by binding of cAMP rather than by protein phosphorylation.
