Fig. 1.
Schematic diagram of proposed cAMP signaling compartments in HASM cells. Two main cAMP signaling compartments have been defined, one centered around β2AR-AC6 in lipid raft domains (consisting of sphingolipid, shown in red, and cholesterol) and another around EP2/4R-AC2 in nonraft domains (consisting of phospholipid, shown in blue). Illustrated are the main AKAP and PDE isoforms known to assemble in these signaling complexes or regulate cAMP emanating from each location. Cytoskeletal elements likely also form barriers to cAMP diffusion. Cell responses that have been linked to specific compartments are listed. A number of AKAP and PDE isoforms are expressed in HASM but the locations of some are unknown, and thus are not shown. These include PDE3, AKAP2, AKAP3, ezrin, and Map2B. It is also unknown if PDE4D splice variants have different localizations. PDE8A is located in lipid rafts where it regulates β2AR-AC6 signaling, but it is unknown how it is tethered specifically in this location. AKAP12 (gravin), AKAP5 (AKAP79), AKAP9 (yotiao).