Question

How would over expression of protein phosphatase 1 affect the induction of cAMP-inducible genes in response to hormone stimulation of target cells? Would protein phosphatase 1 affect the function of cAMP-gated ion channels? Why or why not?

Answer 1

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.