Volume 188, no. 13, p. 4970-4977, 2006. Page 4970: The title should appear as shown above.
Page 4970: There should be a second footnote, reading as follows.
† Publication 18351-MEM from the Scripps Research Institute.
Page 4976, Acknowledgments, the following sentence should be added to the first paragraph: The proteins used in this study were purified by Michael Green, who was supported by grant GM19416 from the National Institute of General Medical Sciences, National Institutes of Health, USPHS, to James A. Hoch, The Scripps Research Institute.