Glycogen debranching enzyme

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amylo-1, 6-glucosidase, 4-alpha-glucanotransferase (glycogen debranching enzyme, glycogen storage disease type III)
Identifiers
Symbol	AGL
Entrez	178
HUGO	321
OMIM	232400
RefSeq	NM_000028
UniProt	P35573
Other data
EC number	2.4.1.25
Locus	Chr. 1 p21

A debranching enzyme is a molecule that helps facilitate the breakdown of glycogen.

Function

Debranching enzymes work by first transferring three glucose subunits of glycogen from one parallel chain to another. This shortens one linear branch while lengthening another. Afterwards, the donator branch will contain only one glucose residue with alpha-1,6 linkage. This remaining residue is in turn cut by the alpha-1,6 glucosidase activity of the debranching enzyme, and attached to the remaining linear branch. This two step process is the general mechanism by which the debranching enzyme "straightens out" glycogen into an unbranched glucose polymer.

These enzymes are important in glycogenolysis because the cutting enzyme, glycogen phosphorylase, cannot cut a non-linear (or branched) glycogen chain.

Enzyme classification

The two debranching enzymes are:

• 4-α-D-glucanotransferase (EC 2.4.1.25) - glucosyltransferase
• amylo-α-1,6-glucosidase (EC 3.2.1.33) - glucosidase

Pathology

Deficiency in either of these enzymes will result in Glycogen storage disease type III.

External links

• MeSH Glycogen+debranching+enzyme

v • d • e Metabolism: carbohydrate metabolism - glycogenesis and glycogenolysis enzymes
Glycogenesis	Phosphoglucomutase - UDP-glucose pyrophosphorylase - Glycogen synthase (Glycogen branching enzyme)
Glycogenolysis	Glycogen phosphorylase (Debranching enzyme) - Phosphoglucomutase - Glycogenin Maltase
Regulation	Phosphorylase kinase - Phosphoprotein phosphatase

v • d • e Transferases: glycosyltransferases (EC 2.4)
2.4.1 - Hexosyltransferases: glucosyltransferase	Phosphorylase (Starch, Glycogen, Myo-) - Glycogen synthase - Debranching enzyme - Branching enzyme - 1,3-beta-glucan synthase - Ceramide glucosyltransferase
2.4.1 - Hexosyltransferases: other	Galactosyltransferase (Lactose synthase, B-N-acetylglucosaminyl-glycopeptide b-1,4-galactosyltransferase) - Glucuronosyltransferase (UGT1A1, UGT2B7, Hyaluronan synthase) - Fucosyltransferase (POFUT1, POFUT2)
2.4.2 - Pentosyltransferases: ADP ribose	Cholera toxin - Diphtheria toxin - Pertussis toxin - Poly ADP ribose polymerase
2.4.2 - Pentosyltransferases: other	Purine nucleoside phosphorylase - Adenine phosphoribosyltransferase - Hypoxanthine-guanine phosphoribosyltransferase - Uracil phosphoribosyltransferase - Amidophosphoribosyltransferase

Template:Sugar hydrolases

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .