Nucleotide Sugar Transporters: Orchestrating Luminal Glycosylation in Plants

Eukaryotic glycobiology revolves around nucleotide sugar transporters (NSTs), which are critical for glycan biosynthesis in the Golgi apparatus and endoplasmic reticulum. In plants, NSTs share similarities with triose phosphate translocators (TPTs) and together form the NST/TPT superfamily. Major research efforts over the last decades have led to the biochemical characterization of several of these transporters and addressed their role in cell wall polysaccharide and glycoconjugate biosynthesis, revealing precise substrate specificity and function. While recent insights gained from NST and TPT crystal structures promise to unravel the molecular mechanisms governing these membrane proteins, their regulation and dynamic behavior remain enigmatic. Likewise, many uncharacterized and orphan NSTs pose exciting questions about the biology of the endomembrane system. We discuss the progress in this active research area and stimulate consideration for the intriguing outstanding questions with a view to establish a foundation for applications in plant engineering and biopolymer production.