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[edit]
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[edit]
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[edit]
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Core 1, Core 2, and Poly-N-acetyllactosamine structures
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Sugars that form the H, A, and B antigens
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PSGL-1 structure showing O-glycans present
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O-GlcNAc modification by OGT and OGA
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Common O-glycans found on alpha-dystroglycan
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Sugars that compose heparan sulphate and keratan sulphate
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Structure of galactosylceramide and glyucosylceramide
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