The regulatory subunit of a mutant protein kinase A (PKA) contains an amino acid substitution that prevents the binding of cAMP. As a consequence of this mutation, which of the following hormone responses is most likely to be decreased? A) 1,25-dihydroxycholecalciferol B) estrogen C) glucagon D) insulin E) thyroxine (T₄)

Question

Quizplus · Accepted Answer

Glucagon exerts its effects by increasing cAMP levels, which activate PKA. A mutation preventing cAMP binding to PKA would decrease glucagon's ability to activate PKA, thus reducing its response.

The Regulatory Subunit of a Mutant Protein Kinase a (PKA)