Guanylate cyclase is an enzyme that plays a crucial role in cellular signaling. It converts GTP (guanosine triphosphate) into cGMP (cyclic guanosine monophosphate), a secondary messenger involved in various physiological processes, including vasodilation and neurotransmission. There are two main types of guanylate cyclase: soluble guanylate cyclase, which is activated by nitric oxide, and membrane-bound guanylate cyclase, which is activated by specific ligands such as natriuretic peptides. The production of cGMP leads to various cellular responses, including relaxation of smooth muscle and regulation of blood pressure.