Allosteric regulation of protein kinase a by nucleotides and metal ions

Protein Kinase A (PKA) is a macromolecular assembly composed of a catalytic subunit (PKA-C) and a regulatory subunit (PKA-R) that harbors cyclic-nucleotide binding (CNB) domains. During its phosphorylation cycle, PKA-C experiences different conformational states that depend on binding of the nucleotides, metal ions and substrates to its active site. How the conformational changes in PKA-C allosterically modulate interactions with the CNB domains of PKA-R is currently unknown. Here we use optical tweezers to selectively manipulate one CNB domain (termed CNB-A) of PKA-R in the presence of PKA-C and different nucleotides.