N-Acetylgalactosamine (also called GalNAc, 2-Acetamido-2-deoxy-D-galactopyranose or N-Acetyl-D-galactosamine) is a monosaccharide derivative of glucose. In humans it is the terminal carbohydrate forming the antigen of blood group A. N-acetylgalactosamine is necessary for intercellular communication, and is concentrated in sensory nerve structures of both humans and animals.

Membrane biology