Synthesizes cyclic GMP (cGMP) from GTP, after activation by heterotrimeric or monomeric G proteins (PubMed:11237875, PubMed:11522784, PubMed:11777934). Involved in chemotaxis (PubMed:11777934). GTP = 3',5'-cyclic GMP + diphosphate Binds 2 magnesium ions per subunit. Activated by guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) (PubMed:11522784, PubMed:11777934). Inhibited by calcium (PubMed:11777934). Homodimer. Highly expressed in vegetative cells; expression decreases approximately 3-fold during the aggregation stage, and then increases again during the later stages of development (mound, finger and slug). By cAMP and osmotic shock. Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.