In the version of this article originally published, the amino acid sequence for Tα1 described in the Online Methods is incorrect. The sequence is described as "Ac-SDAAVDTSSEITTJDLKEKKEVVEEAEN-OH". It should be "Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN-OH". The error has been corrected in the HTML and PDF versions of this article.