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 trans
membrane 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 Ca
2+ 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.
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