Adenylate cyclase (adenylyl cyclase, AC) is an enzyme with crucial regulatory roles in basically all cells. It is the most polyphyletic acknowledged enzyme: six distinctive courses have been explained, all catalyzing the exact same response but symbolizing unrelated gene households with no acknowledged sequence or structural homology. The finest identified AC class is class III or AC-III (Roman numerals are applied for courses). AC-III takes place widely in eukaryotes and has crucial roles in many human tissues. All courses of AC catalyze the conversion of adenosine triphosphate (ATP) to 3′,5′-cyclic AMP (cAMP) and pyrophosphate. Magnesium ions are generally needed and seems to be carefully concerned in the enzymatic mechanism.