Guanylate cyclase (EC 4.6.1.2, also known as guanylyl cyclase or GC) is a lyase enzyme. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. In Biochemistry, a lyase is an Enzyme that catalyzes the breaking of various Chemical bonds by means other than Hydrolysis and Oxidation Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins
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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. Guanosine-5'-triphosphate ( GTP) is a Purine Nucleotide. One role is as substrate for the synthesis of RNA during transcription. Cyclic guanosine monophosphate ( cGMP) is a Cyclic nucleotide derived from Guanosine triphosphate (GTP In Chemistry, the Anion, the Salts and the Esters of Pyrophosphoric acid are called pyrophosphates. Guanosine-5'-triphosphate ( GTP) is a Purine Nucleotide. One role is as substrate for the synthesis of RNA during transcription. Cyclic guanosine monophosphate ( cGMP) is a Cyclic nucleotide derived from Guanosine triphosphate (GTP
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). An enzyme-linked receptor is a Transmembrane receptor, where the binding of an extracellular Ligand causes Enzymatic activity on the intracellular side Natriuretic peptide refers to a Peptide which induces Natriuresis (the discharge of Sodium through Urine) Atrial natriuretic peptide ( ANP) atrial natriuretic factor ( ANF) or atriopeptin, is a protein ( Polypeptide) Hormone secreted (NPR1/GUCY2A, NPR2/GUCY2B)
- GC-C for guanylin and uroguanylin. Guanylin is a 15 Amino acid peptide that is secreted by Goblet cells in the colon. Uroguanylin is a 16 Amino acid Peptide that is secreted by Enterochromaffin cells in the Duodenum and proximal Small intestine. (See also guanylyl cyclase c). Guanylyl cyclase c, or GC-C, is an Enzyme found only in the lumen|luminal aspect of intestinal Epithelium. (GUCY2C)
- Others: (GUCY2D, GUCY2E, GUCY2F)
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 GUCY1A2, GUCY1A3, GUCY1B2 and GUCY1B3.
Function
Once formed, cGMP can be degraded by phosphodiesterases, which themselves are under different forms of regulation, depending on the tissue. A phosphodiesterase is any Enzyme that breaks a Phosphodiester bond.
Like cAMP, cGMP is known to regulate many cellular proteins, such as protein kinases, ion channels, and phosphodiesterases. A protein kinase is a Kinase Enzyme that modifies other Proteins by chemically adding Phosphate groups to them ( Phosphorylation) Ion channels are pore-forming Proteins that help establish and control the small Voltage Gradient across the Plasma membrane of all living
See also
External links
A guanylate cyclase activator (or "GUCA" is one of group of proteins which upregulates Guanylate cyclase. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and booksDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic