Tesmer, J. J. G., Dessauer, C. A., Sunahara, R. K., Murray, L. D., Johnson, R. A., Gilman, A. G. and Sprang, S. R., Biochemistry, 2000, 39, 14464.

Adenylyl cyclases are integral membrane proteins, for which at least 9 isoforms have been characterised by molecular biology approaches.  They are composed of two bundles of six transmembrane helices, with two catalytic domains found as intracellular loops extending into the cytoplasm.

This structure shows a Gs (stimulatory Galpha) subunit in complex with adenylyl cyclase (2 catalytic subunits, C1A and C2A).  The Gs subunit has been locked in its active state by the use of the non-hydrolysable GTP analogue GTPgammaS (GSP).  Similarly, adenylyl cyclase activity has been blocked by the use of a dideoxy ATP analogue.  This is found in the complex as 2',5'-dideoxy-adenosine 3'-monophosphate (1O3) and triphosphate (3PO).  Lastly, the adenylyl cyclase activator forskolin (FOK) is bound to the adenylyl cyclase catalytic subunits.