Adenylate cyclase

Adenylate cyclase is a lyase, an enzyme that catalyzes the reaction ATP to cAMP. cAMP is an important molecule in eukaryotic signal transduction, a so-called second messenger. The adenylate cyclase is activated by other proteins, the GTPases (aka G proteins). There are eight known classes of adenylate cyclases known in mammals.

Structure

Adenylate cyclase is a transmembrane protein. It passes through the plasma membrane twelve times. The important parts for its function are located in the cytoplasmatic N- and C-termini, as well as in the C1 domain, a large loop between transmembrane helix six and seven that extends into the cytoplasm as well.

Catalyzed reaction

Regulation

Adenylate cyclase is stimulated by G proteins, and by forskolin, as well as other class-specific substrates. The classes I, III and VIII are also reculated by Ca²⁺/calmodulin. In neurons, adenylate cyclases are located next to calcium ion channels for faster reaction to Ca²⁺ influx; they are suspected of playing an important role in learning processes. This is supported by the fact that adenylate cyclases are coincidence detectors, meaning that they are only activated by several different signals occurring together.