Origin of cytoplasmic GDP-fucose determines its contribution to glycosylation reactions

Biosynthesis of macromolecules requires precursors such as sugars or amino acids, originating from exogenous/dietary sources, reutilization/salvage of degraded molecules, or de novo synthesis. Since these sources are assumed to contribute to one homogenous pool, their individual contributions are often overlooked. Protein glycosylation uses monosaccharides from all the above sources to produce nucleotide sugars required to assemble hundreds of distinct glycans. Here, we demonstrate that cells identify the origin/heritage of the monosaccharide, fucose, for glycosylation.