You Are Interested in How Cyclic-AMP-Dependent Protein Kinase a (PKA)

You are interested in how cyclic-AMP-dependent protein kinase A (PKA) functions to affect learning and memory, and you decide to study its function in the brain.It is known that, in the cells you are studying, PKA works via a signal transduction pathway like the one depicted in Figure 16-15.Furthermore, it is also known that activated PKA phosphorylates the transcriptional regulator called Nerd that then activates transcription of the gene Brainy.Which situation described below will lead to an increase in Brainy transcription? Figure 16-15

A) a mutation in the Nerd gene that produces a protein that cannot be phosphorylated by PKA
B) a mutation in the nuclear import sequence of PKA from PPKKKRKV to PPAAAAAV
C) a mutation in the gene that encodes cAMP phosphodiesterase that makes the enzyme inactive
D) a mutation in the gene that encodes adenylyl cyclase that renders the enzyme unable to interact with the α subunit of the G protein