catalytic activity:GTP = 3',5'-cyclic GMP + diphosphate.,cofactor:Binds 1 or 2 heme groups per heterodimer.,enzyme regulation:Activated by nitric oxide in the presence of magnesium or manganese ions.,miscellaneous:There are two types of guanylate cyclases: soluble forms and membrane-associated receptor forms.,similarity:Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.,similarity:Contains 1 guanylate cyclase domain.,subunit:Heterodimer of an alpha and a beta chain.,