glycoconjugaten

Glycoconjugates are molecules in which carbohydrates are covalently attached to non-carbohydrate moieties, usually proteins or lipids. They are widespread across all domains of life and display immense structural and functional diversity. Through their glycan components, glycoconjugates mediate cell recognition, signaling, adhesion, and protection against proteolysis, contributing to development, immune responses, and tissue organization.

The main classes of glycoconjugates include glycoproteins, proteoglycans, glycolipids, and glycosylphosphatidylinositol (GPI)-anchored proteins. Glycoproteins bear oligosaccharide chains linked to amino acids in proteins, primarily through N- or O-linkages. Proteoglycans consist of a core protein bearing one or more long glycosaminoglycan chains and are major components of the extracellular matrix and cell surfaces. Glycolipids are lipids with attached carbohydrate moieties that participate in membrane structure and cell signaling. GPI-anchored proteins are tethered to the cell membrane by a glycosylphosphatidylinositol anchor. In bacteria, glycoconjugates also include lipopolysaccharides and related structures that contribute to outer-m membrane integrity and immune interactions.

Biosynthesis typically occurs in the secretory pathway, notably the endoplasmic reticulum and Golgi apparatus. N-linked and O-linked glycosylation are common modes for attaching glycans to proteins, mediated by a suite of glycosyltransferases and donor sugars. The specific glycan structures influence protein folding, stability, trafficking, and interactions.

Clinical and research relevance is broad: altered glycosylation is linked to congenital disorders of glycosylation, cancer progression, and immune evasion. Glycoconjugates also provide diagnostic markers and therapeutic targets, and are central to vaccine design and biopharmaceutical development.