Gal14GlcNAc

Gal14GlcNAc, commonly written Galβ1-4GlcNAc, is a disaccharide consisting of galactose linked to N-acetylglucosamine via a beta-1,4 bond. It is the canonical unit of N-acetyllactosamine (LacNAc), a motif frequently found in glycans.

In glycans, Galβ1-4GlcNAc forms the core repeating LacNAc unit that appears in many N-linked and O-linked glycans and can extend into long poly-LacNAc chains decorating glycoproteins and glycolipids. The GlcNAc residue is typically attached to the underlying protein or lipid, while the galactose is added by beta-1,4-galactosyltransferases using UDP-galactose as donor.

Biological significance lies in its role as a recognition motif. LacNAc units are ligands for lectins such as galectins, influencing cell–cell interactions, receptor signaling, and immune recognition. They can also serve as substrates for further glycan elaboration and are sometimes altered in development or disease, including cancer, where LacNAc-containing structures may be up- or down-regulated.

Analytical notes: LacNAc-containing motifs are routinely studied in glycobiology using exoglycosidase digestion and mass spectrometry or chromatographic methods to identify and characterize glycan structures. Synonyms for Gal14GlcNAc include LacNAc and Galβ1-4GlcNAc; the term Gal14GlcNAc is a shorthand used in some databases and literature.