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Glycogenin

 

 
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Glycogenin
 
 
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Glycogenin is an enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
 involved in glycogen
Glycogen

Glycogen is a polysaccharide of glucose which functions as the secondary short term energy storage in animal cells. It is made primarily by the liver and the muscles, but can also be made by the brain and stomach....
 biosynthesis
Biosynthesis

Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyst by enzymes....
. This enzyme was discovered by Dr. William J. Whelan, a fellow of the Royal Society of London and current professor of Biochemistry at the University of Miami
University of Miami

The University of Miami is a private, non-sectarian university founded in 1925 in the city of Coral Gables, Florida, Florida, United States, a historic suburb of Miami, Florida....
. It is a homodimer of 37-kd subunits and is classified as a glycosyltransferase
Glycosyltransferase

Glycosyltransferases are enzymes that act as a catalyst for the transfer of a monosaccharide unit from an activated sugar phosphate to an acceptor molecule, usually an alcohol....
.

Function
The main enzyme involved in glycogen polymerisation. Glycogen synthase
Glycogen synthase

Glycogen synthase is a glycosyltransferase enzyme that catalyses the reaction of UDP-glucose and n to yield Uridine diphosphate and n+1....
 can only add to an existing chain of at least 4 glucose
Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
 residues.






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Encyclopedia


Glycogenin is an enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
 involved in glycogen
Glycogen

Glycogen is a polysaccharide of glucose which functions as the secondary short term energy storage in animal cells. It is made primarily by the liver and the muscles, but can also be made by the brain and stomach....
 biosynthesis
Biosynthesis

Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyst by enzymes....
. This enzyme was discovered by Dr. William J. Whelan, a fellow of the Royal Society of London and current professor of Biochemistry at the University of Miami
University of Miami

The University of Miami is a private, non-sectarian university founded in 1925 in the city of Coral Gables, Florida, Florida, United States, a historic suburb of Miami, Florida....
. It is a homodimer of 37-kd subunits and is classified as a glycosyltransferase
Glycosyltransferase

Glycosyltransferases are enzymes that act as a catalyst for the transfer of a monosaccharide unit from an activated sugar phosphate to an acceptor molecule, usually an alcohol....
.

Function


The main enzyme involved in glycogen polymerisation. Glycogen synthase
Glycogen synthase

Glycogen synthase is a glycosyltransferase enzyme that catalyses the reaction of UDP-glucose and n to yield Uridine diphosphate and n+1....
 can only add to an existing chain of at least 4 glucose
Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
 residues. Glycogenin acts as the primer
Primer

Primer can refer to:*Primer , a 2004 feature film written and directed by Shane Carruth*Primer , a device on some gasoline engines used to prime the engine with gasoline before starting it...
, to which further glucose monomer
Monomer

A monomer is a small molecule that may become Chemistry chemical bonding to other monomers to form a polymer....
s may be added. It achieves this by catalyzing
Catalysis

Catalysis is the process in which the reaction rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst....
 the addition of glucose to itself (autocatalysis) by first binding glucose from UDP-glucose to the hydroxyl
Hydroxyl

Hydroxyl in chemistry stands for a molecule consisting of an oxygen atom and a hydrogen atom connected by a covalent bond. The neutral form is a hydroxyl Radical and the hydroxyl anion is called a hydroxide....
 group of Tyr-194. Seven more glucoses can be added, each derived from UDP-glucose, by glycogenin's glucosyltransferase activity. Once sufficient residues have been added, glycogen synthase takes over extending the chain. Glycogenin remains covalently attached to the reducing end of the glycogen molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
.

Evidence accumulates that a priming protein may be a fundamental property of polysaccharide synthesis in general, the molecular details of mammalian glycogen biogenesis may serve as a useful model for other systems.

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