Illustration of AKAP properties. (A) AKAPs share three common properties: 1) AKAPs bind to the regulatory subunit of PKA through a conserved anchoring domain; 2) a unique subcellular targeting domain directs AKAP-signaling complexes to discrete locations inside a cell; and 3) additional binding sites for other signaling proteins such as kinases, phosphatases, or potential substrates. (B) Ribbon diagram of the NMR structure of RIIα (1–43) dimer (yellow, blue, and red) and the AKAP amphipathic helix peptide (green; Newlon et al. 2001) depicted using Accelrys Discovery Studio 2.5.1 based on the coordinates from PDB (http://www.rcsb.org/pdb/explore/explore.do?structureId=2DRN).