Cell-surface N-linked glycans bearing terminal galactose

Cell-surface N-linked glycans bearing terminal galactose are complex carbohydrate structures attached to the asparagine residues of membrane-bound proteins, characterized by a galactose sugar at the non-reducing end. These glycans serve as critical recognition elements in the biological landscape, acting as ligands for various endogenous receptors, most notably the asialoglycoprotein receptor (ASGPR) in the liver and the galectin family of proteins (Stockert, 1995; Cummings & Liu, 2009). Their primary biological roles include mediating the clearance of glycoproteins from the blood, facilitating cell-cell adhesion, and modulating immune system responses (Varki et al., 2015). In pathological conditions such as cancer and chronic inflammation, the expression patterns of these terminal galactose residues are often altered, contributing to disease progression, metastasis, and immune evasion (Pinho & Reis, 2015). From a therapeutic standpoint, these glycans are extensively exploited for targeted drug delivery; for instance, galactose and its derivatives are conjugated to therapeutic oligonucleotides to ensure precise uptake by hepatocytes via ASGPR (Springer & Dowdy, 2018). Furthermore, the interaction between these glycans and galectins is a target for novel inhibitors aimed at treating fibrosis and various malignancies (Johannes et al., 2018).

Other names

Terminal galactose N-glycansGalactosylated N-linked oligosaccharidesAsialoglycansβ-galactoside-terminated glycansTerminal Gal-terminated N-glycans

The primary mechanism involves the utilization of terminal galactose as a targeting ligand for the asialoglycoprotein receptor (ASGPR), which mediates the internalisation of conjugated therapeutic agents into hepatocytes via endocytosis. Additionally, therapeutic strategies involve the use of small molecules or polysaccharides to competitively inhibit the binding of terminal galactose residues to galectins, thereby disrupting pro-fibrotic and pro-inflammatory signaling cascades.