GDP-Man
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Guanosine diphosphate mannose or GDP-mannose is a
nucleotide sugar Nucleotide sugars are the activated forms of monosaccharides. Nucleotide sugars act as glycosyl donors in glycosylation reactions. Those reactions are catalyzed by a group of enzymes called glycosyltransferases. History The anabolism of oligosacch ...
that is a substrate for
glycosyltransferase Glycosyltransferases (GTFs, Gtfs) are enzymes ( EC 2.4) that establish natural glycosidic linkages. They catalyze the transfer of saccharide moieties from an activated nucleotide sugar (also known as the "glycosyl donor") to a nucleophilic gl ...
reactions in
metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...
. This compound is a substrate for enzymes called
mannosyltransferase A mannosyltransferase is a type of glycosyltransferase that acts upon mannose Mannose is a sugar with the formula , which sometimes is abbreviated Man. It is one of the monomers of the aldohexose series of carbohydrates. It is a C-2 epimer of gl ...
s. Known as donor of activated mannose in all glycolytic reactions, GDP-mannose is essential in eukaryotes.


Biosynthesis

GDP-mannose is produced from GTP and
mannose-6-phosphate Mannose-6-phosphate (M6P) is a molecule bound by lectin in the immune system. M6P is converted to fructose 6-phosphate by mannose phosphate isomerase. M6P is a key targeting signal for acid hydrolase precursor proteins that are destined for t ...
by the enzyme mannose-1-phosphate guanylyltransferase (GDP-mannose pyrophosphorylase, GDP-MP). This enzyme belongs to a family of nucleotidyl-transferases and is a pervasive enzyme found in bacteria, fungi, plants, and animals.


References


See also

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Nucleoside Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (ribose or 2'-deoxyribose) whereas a nucleotid ...
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Nucleotide Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...
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Guanosine Guanosine (symbol G or Guo) is a purine nucleoside comprising guanine attached to a ribose ( ribofuranose) ring via a β-N9- glycosidic bond. Guanosine can be phosphorylated to become guanosine monophosphate (GMP), cyclic guanosine monophosp ...
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Guanosine diphosphate Guanosine diphosphate, abbreviated GDP, is a nucleoside diphosphate. It is an ester of pyrophosphoric acid with the nucleoside guanosine. GDP consists of a pyrophosphate group, a pentose sugar ribose, and the nucleobase guanine. GDP is the pr ...
{{Nucleotide sugars Nucleotides Coenzymes