Nature 544, 65–70 (2017); doi:10.1038/nature21725

In this Article, the list of symbols used to depict monosaccharides in the figures is not derived from the Consortium of Functional Glycomics or included in ref. 25. Instead, it follows the current Symbol Nomenclature for Glycans (SNFG) system, which is described in ref. 1. The original Article has not been corrected.