N-acetylmannosaminyltransferase

N-acetylmannosaminyltransferase is an enzyme that plays a crucial role in the biosynthesis of complex carbohydrates. This enzyme is involved in the transfer of N-acetylmannosamine (ManNAc) residues to the growing polysaccharide chain.

Function

N-acetylmannosaminyltransferase is responsible for the addition of N-acetylmannosamine to the growing polysaccharide chain during the biosynthesis of complex carbohydrates. This process is essential for the formation of glycoproteins and glycolipids, which are vital components of all living cells.

The enzyme catalyzes the transfer of a ManNAc residue from UDP-ManNAc to a acceptor molecule, resulting in the formation of a new glycosidic bond. This reaction is a key step in the biosynthesis of sialic acid, a sugar molecule that is often found at the outermost end of glycan chains on the cell surface.

Structure

The structure of N-acetylmannosaminyltransferase is complex and varies among different organisms. However, it typically consists of a large catalytic domain and a smaller substrate-binding domain. The catalytic domain is responsible for the enzymatic activity, while the substrate-binding domain recognizes and binds to the ManNAc residue.

Clinical significance

Mutations in the gene encoding N-acetylmannosaminyltransferase can lead to various diseases. For instance, a deficiency in this enzyme can result in sialuria, a rare metabolic disorder characterized by an excess of free sialic acid in the body fluids.

Furthermore, the enzyme is also implicated in cancer biology. Altered sialylation patterns, which can be caused by changes in the activity of N-acetylmannosaminyltransferase, have been associated with cancer progression and metastasis.

See also

• Enzyme
• Biosynthesis
• Carbohydrate
• Glycoprotein
• Glycolipid
• Sialic acid
• Sialuria

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