1. J. B. Rafferty, S. E. Sedelnikova, D. Hargreaves, P. J. Artymiuk, P. J. Baker, D. W. Rice, Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
2. G. J. Sharples, A. A. Mahdi, R. G. Lloyd, Department of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.