Nature Neuroscience 10, 32–39 (2007); Published online 24 December 2006; corrected after print 23 January 2007

In the version of this article initially published, the authors neglected to cite a closely related paper. At the end of the Introduction, the following sentence should have been included: “During revision of this manuscript, another group published a complex structure named a cross-shaped octamer37 that is identical to the structure reported in this paper.” In the reference list, the following reference should have been included: “37. Pioletti, M., Findeisen, F., Hura, G.L. & Minor, D.L. Jr. Three-dimensional structure of the KChIP1–Kv4.3 T1 complex reveals a cross-shaped octamer. Nat. Struct. Mol. Biol. 13, 987–995 (2006).” The error has been corrected in the PDF version of the article.