Cyclic nucleotide phosphodiesterase with specificity for the second messengers cAMP and cGMP, which are key regulators of many important physiological processes (PubMed:11420239). Has also activity toward cUMP (By similarity). Independently of its catalytic activity it is part of an E2/17beta-estradiol-induced pro-apoptotic signaling pathway. E2 stabilizes the PDE3A/SLFN12 complex in the cytosol, promoting the dephosphorylation of SLFN12 and activating its pro-apoptotic ribosomal RNA/rRNA ribonuclease activity. This apoptotic pathway might be relevant in tissues with high concentration of E2 and be for instance involved in placenta remodeling (By similarity). a nucleoside 3',5'-cyclic phosphate + H2O = a nucleoside 5'-phosphate + H(+) 3',5'-cyclic AMP + H2O = AMP + H(+) 3',5'-cyclic GMP + H2O = GMP + H(+) 3',5'-cyclic UMP + H2O = H(+) + UMP Binds 2 divalent metal cations per subunit. Binds 2 divalent metal cations per subunit. Inhibited by cGMP. Belongs to the cyclic nucleotide phosphodiesterase family. PDE3 subfamily.