Calmodulin-dependent cyclic nucleotide phosphodiesterase with a dual specificity for the second messengers cAMP and cGMP, which are key regulators of many important physiological processes. Has a high affinity for both cAMP and cGMP (PubMed:7568196). Modulates the amplitude and duration of the cAMP signal in sensory cilia in response to odorant stimulation, hence contributing to the generation of action potentials. Regulates smooth muscle cell proliferation. Regulates the stability of growth factor receptors, including PDGFRB (By similarity). a nucleoside 3',5'-cyclic phosphate + H2O = a nucleoside 5'-phosphate + H(+) 3',5'-cyclic GMP + H2O = GMP + H(+) 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. Site 2 has a preference for magnesium ions. Type I PDE are activated by the binding of calmodulin in the presence of Ca(2+). Homodimer. Highly expressed in olfactory epithelium and at moderate levels, in cerebellum, as well as weakly in forebrain, testis, heart and lung (PubMed:7568196). In the olfactory epithelium, expressed by sensory neurons, but not epithelial cells (PubMed:7568196). Belongs to the cyclic nucleotide phosphodiesterase family. PDE1 subfamily.