Nat. Struct. Mol. Biol. 22, 803–808 (2015); published online 14 September 2015; corrected after print 12 April 2016

In the version of this article initially published, the Protein Data Bank accession code for the coordinates and structure factors for SLC26DgΔSTAS (PDB 5IOF) was not included. The error has been corrected in the HTML and PDF versions of the article.