All known effects of cyclic AMP in eukaryotic cells results from ?

Ans. 'c' i.e., Activation of protein kinase o Cyclic AMP exes most of its effects by stimulating cAMP-dependent protein kinases. These kinases are composed of a cAMP-binding regulatory (R) dimer and two catalytic (C) chains. When cAMP binds to the R dimer, active C chains are released to diffuse through the cytoplasm and nucleus, where they transfer phosphate from ATP to appropriate substrate proteins, often enzymes. The specificity of cAMP's regulatory effects resides in the distinct protein substrates of the kinases that are expressed in different cells. For example, liver is rich in phosphorylase kinase and glycogen synthase, enzymes whose reciprocal regulation by cAMP-dependent phosphorylation gov erns carbohydrate storage and release.