(Downloading may take up to 30 seconds. If the slide opens in your browser, select File -> Save As to save it.)

Click on image to view larger version.

Figure 1

cAMP signal pathways. Ligand binding to various G protein-coupled receptors (GPCRs) activates adenylyl cyclase in their proximity and generates pools of cAMP. The local concentration and distribution of the cAMP gradient are limited by phosphodiesterases (PDEs). Particular GPCRs are confined to specific domains of the cell membrane in association with intracellular organelles or cytoskeletal constituents. The subcellular structures may harbor specific isozymes of PKA that, through anchoring via AKAPs, are localized in the vicinity of the receptor and the cyclase. PDEs are also anchored and serve to limit the extension and duration of cAMP gradients. These mechanisms serve to localize and limit the assembly and triggering of specific pathways to a defined area of the cell close to the substrate. cAMP (red filled circles) has effects on a range of effector molecules encompassing 1) PKA, 2) PDEs, 3) guanine nucleotide exchange factors (GEFs) known as exchange proteins activated by cAMP (Epacs), and 4) cyclic nucleotide-gated ion channels.

This Article

  1. J Mol Endocrinol vol. 44 no. 5 271-284