Catalyzes the formation of the signaling molecule cAMP (PubMed:9874775). May function as sensor that mediates responses to changes in cellular bicarbonate and CO(2) levels (By similarity). Has a critical role in mammalian spermatogenesis by producing the cAMP which regulates cAMP-responsive nuclear factors indispensable for sperm maturation in the epididymis. Induces capacitation, the maturational process that sperm undergo prior to fertilization (By similarity). Involved in ciliary beat regulation (By similarity). ATP = 3',5'-cyclic AMP + diphosphate Binds 2 magnesium ions per subunit (By similarity). Is also active with manganese (in vitro) (PubMed:9874775). Activated by manganese or magnesium ions (PubMed:9874775). In the presence of magnesium ions, the enzyme is activated by bicarbonate (PubMed:12609998). Calcium mildly increases the enzyme activity, also in the presence of magnesium ions. Distributed to subcellular compartments containing cAMP targets. Found as a plasma membrane-associated protein, protein concentrated in the perinuclear region and protein colocalized with actin or tubulin. A number of isoforms are produced. Detected in testis (at protein level). Preferentially expressed in testis. The N-terminal guanylate cyclase domains are required for enzyme activity. Fragments containing the first 470 amino acid residues are fully active. Cleavage may occur to generate the active 48 kDa form. Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.