Guanylate cyclase (, also known as guanylyl cyclase or GC) is a lyase, an enzyme that catalyzes the conversion of guanosine triphosphate (GTP) to 3',5'-cyclic guanosine monophosphate (cGMP) and pyrophosphate. There are soluble and membrane-bound forms of guanylyl cyclases. Soluble GC (sGC) is activated by nitric oxide, most notably involved in vasodilation. Membrane-bound forms are receptors: GC-A & GC-B for natriuretic factors such as atrial natriuretic factor (ANF), and GC-C for guanylin and uroguanylin. It can also be regulated by calcium.

EC 4.6.1 | Hemoproteins