Galactose-alpha-1,3-galactose

Galactose-alpha-1,3-galactose

Galactose-alpha-1,3-galactose (also known as Alpha-gal) is a carbohydrate molecule that is present in most mammals, but not in humans. It is a disaccharide, meaning it is composed of two sugar molecules, specifically two galactose molecules. The molecule is produced by a specific enzyme known as alpha-1,3-galactosyltransferase (α1,3GT).

Structure and Synthesis

The structure of Galactose-alpha-1,3-galactose is characterized by a galactose molecule linked to another galactose molecule via an alpha-1,3-glycosidic bond. This bond is formed by the enzyme alpha-1,3-galactosyltransferase, which transfers a galactose unit from a donor molecule to an acceptor molecule.

The synthesis of Alpha-gal occurs in the Golgi apparatus of cells, where the enzyme α1,3GT is located. The enzyme transfers a galactose molecule from a donor molecule, such as UDP-galactose, to an acceptor molecule, forming the alpha-gal epitope.

Role in Immune Response

In humans, the immune system recognizes Alpha-gal as a foreign substance and produces IgE antibodies against it. This can lead to an allergic reaction known as Alpha-gal syndrome, which is characterized by a delayed allergic reaction to the consumption of red meat.

Alpha-gal Syndrome

Alpha-gal syndrome is a recently identified type of food allergy to red meat. In the United States, the condition most often begins when a Lone Star tick bite transmits a sugar molecule called alpha-gal into the body. This can trigger an immune system reaction that later produces mild to severe allergic reactions to red meat, such as beef, pork or lamb.

See Also

• Galactose
• Alpha-1,3-galactosyltransferase
• Alpha-gal syndrome
• Golgi apparatus
• IgE antibodies

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