Hydrolyzes the second messenger cAMP, which is a key regulator of many important physiological processes. 3',5'-cyclic AMP + H2O = AMP + H(+) Binds 2 divalent metal cations per subunit. Site 1 may preferentially bind zinc ions. Binds 2 divalent metal cations per subunit (By similarity). Site 2 has a preference for magnesium and/or manganese ions (By similarity). Purine metabolism; 3',5'-cyclic AMP degradation; AMP from 3',5'-cyclic AMP: step 1/1. Part of a complex containing AKAP5, ADCY5, ADCY6 and PKD2. Belongs to the cyclic nucleotide phosphodiesterase family. PDE4 subfamily.