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