Nat. Methods 10, 1099–1101 (2013); published online 15 September 2013; corrected after print 5 May 2014

In the version of this article initially published, the authors did not acknowledge all of the people involved in the generation of the crystallographic data set of AF1503 from A. fulgidus. These diffraction data were originated by M. Hulko, A. Ursinus, K. Bär, J. Martin, K.Z. and A.N. Lupas at the Max Planck Institute for Developmental Biology, Tübingen. M. Hulko, A. Ursinus, K. Bär, J. Martin and A.N. Lupas have kindly given their retroactive permission to use the data. Their report on the AF1503 structure was published in the Journal of Structural Biology (10.1016/j.jsb.2014.02.008) and PDB 4CQ4. The error has been corrected in the HTML and PDF versions of the article.