Guanylate cyclase

Guanylate cyclase (, also known as guanylyl cyclase or GC) is a lyase enzyme.

Reaction
It catalyzes the conversion of guanosine triphosphate (GTP) to 3',5'-cyclic guanosine monophosphate (cGMP) and pyrophosphate:

Types
There are membrane-bound (type 1) and soluble (type 2) forms of guanylyl cyclases.

Membrane-bound
Membrane-bound (type 1) guanylyl cyclase is a single transmembrane protein and acts as an ANP receptor ..(Compare it with Adenylate Cyclase which is 12 transmembrane protein )
 * Another type of Type 1 receptor binds to the ST E Coli enterotoxin and the gastrointestinal poly peptide Guanylin.
 * Membrane-bound forms are enzyme-linked receptors:
 * GC-A & GC-B for natriuretic factors such as atrial natriuretic factor (ANF). (/GUCY2A, /GUCY2B)
 * GC-C for guanylin and uroguanylin. (See also guanylyl cyclase c).
 * Others:

Soluble
Soluble (type 2) guanylyl cyclase (sGC) is a receptor for NO (thus also called NO receptor). It is soluble i.e. completely intracellular. It is most notably involved in vasodilation. It is encoded by the genes, , and.

Function
Once formed, cGMP can be degraded by phosphodiesterases, which themselves are under different forms of regulation, depending on the tissue.

Like cAMP, cGMP is known to regulate many cellular proteins, such as protein kinases, ion channels, and phosphodiesterases.