Phosphodiesterase specific for extracellular cAMP. Involved in the degradation of extracellular cAMP specifically during multicellular development. 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. Inhibited by 3-isobutyl-1-methylxanthine (IBMX). Low expression during growth and cell aggregation (up to 6 hours), maximally increases after 9 hours of starvation, during the mound stage. Remains expressed at significant levels during the other stages of multicellular development. Null cells show a reduction of phosphodiesterase activity on the cell surface. Aggregation speed is similar, but from the mound stage until fruiting body formation it is slower. Aggregates largely remain as mounds; after 15 hours (compared to slugs in wild type cells), after 20 hours (compared to culmination state in wild type cells) and after 27 hours (compared to completion of fruiting body formation in wild type cells). Thus, slug formation and culmination appear to be affected. These processes were not only slower but also less slugs and fruiting bodies are formed. Belongs to the cyclic nucleotide phosphodiesterase family. Extended N-terminus.