O-linked glycosylation

O-linked glycosylation is a specific type of glycosylation where a sugar molecule is attached to an oxygen atom in the amino acid residues of a protein. This process is a crucial part of protein folding and stability, and plays a significant role in cell-cell interactions and cell signaling.

Process

O-linked glycosylation occurs in the Golgi apparatus of the cell. The process begins with the transfer of a N-acetylgalactosamine (GalNAc) to the hydroxyl group of a serine or threonine residue in the protein. This initial step is catalyzed by a family of enzymes known as polypeptide N-acetylgalactosaminyltransferases (ppGalNAcTs).

Following the initial attachment of GalNAc, additional sugars such as galactose and sialic acid can be added to form a variety of complex oligosaccharides. The addition of these sugars is catalyzed by a series of specific glycosyltransferases.

Function

O-linked glycosylation has a wide range of functions in the cell. It plays a crucial role in protein folding and stability, and can influence protein activity and localization. In addition, O-linked glycosylation is involved in cell-cell interactions, including cell adhesion and immune response.

Abnormalities in O-linked glycosylation can lead to a variety of diseases, including cancer, autoimmune diseases, and congenital disorders of glycosylation.

See also

• N-linked glycosylation
• Glycosylation
• Protein folding
• Cell signaling