Catalyzes the formation of the signaling molecule cAMP in response to G-protein signaling. Participates in signaling cascades triggered by odorant receptors via its function in cAMP biosynthesis. Required for the perception of odorants. Required for normal sperm motility and normal male fertility. Plays a role in regulating insulin levels and body fat accumulation in response to a high fat diet. ATP = 3',5'-cyclic AMP + diphosphate Binds 2 magnesium ions per subunit. Is also active with manganese (in vitro). Activated by forskolin. After forskolin treatment, activity is further increased by calcium/calmodulin. In the absence of forskolin, calcium/calmodulin has little effect on enzyme activity. Also detected in the cytoplasm, close to lipid droplets. Detected in zona glomerulosa and zona fasciculata in the adrenal gland (at protein level) (PubMed:11549699). Expressed in brain, heart, kidney, liver, lung, pancreas islets, placenta, and skeletal muscle (PubMed:9920776). Detected in testis (PubMed:15705663). The protein contains two modules with six transmembrane helices each; both are required for catalytic activity. Isolated N-terminal or C-terminal modules have no catalytic activity, but when they are brought together, enzyme activity is restored. The active site is at the interface of the two modules. Sumoylated. Sumoylation is required for targeting ot olfactory cilia. N-glycosylated. Rapidly phosphorylated after stimulation by odorants or forskolin. Phosphorylation by CaMK2 at Ser-1076 down-regulates enzyme activity. Genetic variations at the ADCY3 locus define the body mass index quantitative trait locus 19 (BMIQ19) [MIM:617885]. Variance in body mass index is a susceptibility factor for obesity. Disease susceptibility is associated with variants affecting the gene represented in this entry. Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.