Bifunctional Monosaccharides Preferentially Localize to Nuclear Subcompartments

Recent progress in glycan research has been driven by widespread implementations of metabolic oligosaccharide engineering. Complementing existing approaches, we here introduce bifunctional, UV‐crosslinkable, and clickable N‐acetylglucosamine and N‐acetylgalactosamine analogues, which enable direct visualization of the intracellular probe distribution as well as distinguishing monomeric and macromolecule‐bound fractions. Using this feature, we find that monomeric N‐acetylmonosaccharides partition into RNA‐rich nuclear compartments such as nuclear speckles and nucleoli. This suggests the existence of spatially separated N‐acetylmonosaccharide pools within the nucleoplasm. Taken together, bifunctional N‐acetylmonosaccharide probes are versatile discovery tools for probing intracellular localization of monosaccharides.