AKAP is the acronym for A-kinase anchoring protein. AKAPs are a family of functionally related proteins that bind the regulatory (R) subunit of cAMP-dependent protein kinase A (PKA) with high affinity. They target the kinase to specific subcellular organelles. This type of subcellular localization is a mechanism of compartmentalization of PKA. The compartmentalization of signal transduction enzymes into signaling complexes is an important mechanism to ensure the specificity of intracellular events. In part, the preferential phosphorylation of specific proteins by PKA is thus mediated by the anchoring of PKA to AKAPs that are positioned in close proximity to target proteins. A whole family of AKAPs exist but for most of them only little is known about their exact function.