Nat. Struct. Mol. Biol. 18, 423–431 (2011); published online 27 March 2011; corrected after print 21 September 2011
In the version of this article initially published, panels in Figures 2b (middle row, Dex-LWH), 3b (0.1mM CPT) and 3d (0.1mM CPT) were mistakenly replaced with duplicates of adjacent panels. The errors have been corrected in the HTML and PDF versions of the article.
The online version of the original article can be found at 10.1038/nsmb.2038