Has guanylyl cyclase on binding to the beta-1 subunit. GTP = 3',5'-cyclic GMP + diphosphate Activated by nitric oxide in the presence of magnesium or manganese ions. Heterodimer of an alpha and a beta chain. There are two types of guanylate cyclases: soluble forms and membrane-associated receptor forms. Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.