These sequences are functionally identified as members of the adenylate cyclase family, which catalyses the conversion of ATP to 3',5'-cyclic AMP and pyrophosphate. Six distinct non-homologous classes of AC have been identified. The structure of three classes of adenylyl cyclases have been solved [3].

1: Aeromonas hydrophila adenylyl cyclase 2: a new class of adenylyl cyclases with thermophilic properties and sequence similarities to proteins from hyperthermophilic archaebacteria. Sismeiro O, Trotot P, Biville F, Vivares C, Danchin A; J Bacteriol 1998;180:3339-3344. PMID:9642185

2: The catalytic domains of thiamine triphosphatase and CyaB-like adenylyl cyclase define a novel superfamily of domains that bind organic phosphates. Iyer LM, Aravind L; BMC Genomics 2002;3:33-33. PMID:12456267

3: Structure of the class IV adenylyl cyclase reveals a novel fold. Gallagher DT, Smith NN, Kim SK, Heroux A, Robinson H, Reddy PT; J Mol Biol. 2006;362:114-122. PMID:16905149

4: Crystallization of the class IV adenylyl cyclase from Yersinia pestis. Smith N, Kim SK, Reddy PT, Gallagher DT; Acta Crystallograph Sect F Struct Biol Cryst Commun. 2006;62:200-204. PMID:16511301