Plays a role in signal transduction by regulating the intracellular concentration of cyclic nucleotides (PubMed:10373451, PubMed:10393245, PubMed:16330539, PubMed:27058447, PubMed:17389385). Can hydrolyze both cAMP and cGMP, but has higher affinity for cAMP and is more efficient with cAMP as substrate (PubMed:10373451, PubMed:10393245, PubMed:27058447, PubMed:17389385). May play a critical role in regulating cAMP and cGMP levels in the striatum, a region of the brain that contributes to the control of movement and cognition (PubMed:27058447). 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(+) 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. Inhibited by dipyridamole and moderately by IBMX. cGMP acts as an allosteric activator. Purine metabolism; 3',5'-cyclic AMP degradation; AMP from 3',5'-cyclic AMP: step 1/1. Purine metabolism; 3',5'-cyclic GMP degradation; GMP from 3',5'-cyclic GMP: step 1/1. Homodimer. Isoforms differ in their N-terminal region. Abundant in the putamen and caudate nucleus regions of brain and testis, moderately expressed in the thyroid gland, pituitary gland, thalamus and cerebellum. The tandem GAF domains bind cAMP, and regulate enzyme activity. The binding of cAMP stimulates enzyme activity. Composed of a C-terminal catalytic domain containing two divalent metal sites and an N-terminal regulatory domain which contains one cyclic nucleotide-binding region. Phosphorylated on Thr-16. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the cyclic nucleotide phosphodiesterase family. Extended N-terminus.