Adenylate Cyclase

Adenylate cyclase (AC) (ATP diphosphate-lyase cyclizing; EC 4.6.1.1) forms part of the adenylate cyclase signaling system and catalyzes the synthesis of cyclic adenosine monophosphate (cAMP) from ATP. ACs are widespread signaling proteins, which translate diverse intracellular and extracellular stimuli into a uniform intracellular signal. ACs are currently divided into six unrelated classes, five of which (classes I, II, IV, V, VI) have not been studied in great detail, mostly because they are limited to a narrow range of prokaryotic species.Class III, finally, is the numerically largest, structurally and functionally most diverse,and pharmacologically most relevant; it is also the only one occurring in animals. 

References:

1.Bassler J,et al.Cell Signal. 2018 Jun;46:135-144. 
2.Lomovatskaya LA,et al. J Recept Signal Transduct Res. 2008;28(6):531-42.