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Guanylate cyclase (EC 4.6.1.2, also known as guanyl cyclase, guanylyl cyclase, or GC; systematic name GTP diphosphate-lyase (cyclizing; 3′,5′-cyclic-GMP-forming)) is a lyase enzyme that converts guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP) and pyrophosphate: [1] GTP = 3′,5′-cyclic GMP + diphosphate
Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP. Its most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane-impermeable peptide hormones to the external cell surface. [1]
In mammalian cells, cGAMP is synthesized by cyclic GMP-AMP synthase from ATP and GTP upon cytosolic DNA stimulation. [2] cGAMP produced by cGAS contains mixed phosphodiester linkages, with one between 2'-OH of GMP and 5'-phosphate of AMP and the other between 3'-OH of AMP and 5'-phosphate of GMP. [3] [4] [5] [6]
In its Fe(II) form, this heme moiety is the target of nitric oxide, which is synthesized by endothelial cells following appropriate stimulation. Binding of nitric oxide to the heme results in activation of the C-terminal catalytic domain, which produces cGMP from GTP.
The GTP form of the α subunit of transducin (G t) activates the cyclic GMP phosphodiesterase from retinal rod outer segments, [3] and the GTP form of the α subunit of the stimulatory G protein (G s) activates hormone-sensitive adenylate cyclase. [4] [5] More than one type of G protein co-exist in the same tissue. For example, in adipose ...
Guanosine monophosphate (GMP), also known as 5′-guanidylic acid or guanylic acid (conjugate base guanylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase guanine; hence it is a ribonucleotide ...
In capping enzymes, a highly conserved lysine residue serves as the catalytic residue that forms a covalent enzyme-GMP complex. [ 1 ] The transfer RNA (tRNA) for histidine is unique among eukaryotic tRNAs in requiring the addition of a guanine nucleotide before being aminoacylated by the histidine tRNA synthetase .
Retinal 3′,5′-cGMP phosphodiesterase (PDE) is located in photoreceptor outer segments and is an important enzyme in phototransduction. [2]3′,5′-cyclic-nucleotide phosphodiesterases in rod cells are oligomeric, made up of two heavy catalytic subunits, α (90 kDa) and β (85 kDa,) and two lighter inhibitory γ subunits (11 kDa each).