N-acetyllactosamine is a disaccharide from the combination of galactose (yellow circle) and N-acetylglucosamine (GlcNAc, blue square) connected via a β1‑4 glycosidic bond (Figure 412-5). 

N-acetyllactosamine has many roles in glycobiology. It is a component of many glycoproteins (proteins bound with a carbohydrate molecule), a substrate for blood group antigens, and a core structural component of human milk oligosaccharides (HMO) (Fischöder et al., 2017). In HMO synthesis lactose can be extended by the addition of multiple repeat units of N-acetyllactosamine via β1‑3 or β1‑6 glycosidic bond (Figure 412-8) (Bode, 2012).