Compartmentalization of signal transduction enzymes is an important mechanism for imparting cellular signaling specificity. This occurs through the interaction of enzymes with scaffolding or anchoring proteins. To date, one of the best-studied examples of kinase anchoring is the targeting of PKA to cellular locations through its association with A-kinase anchoring proteins (AKAPs). AKAPs mediate a high-affinity interaction with the type II regulatory subunit (RII) of PKA to localize the kinase to pools of cAMP and within proximity of preferred substrates. Furthermore, AKAPs can organize entire signaling complexes made up of kinases, phosphates, and regulatory proteins.