Institution: | (1) Department of Biochemistry, University College London, WC1E 6BT London, U.K.;(2) Department of Biochemistry, University of Leicester, LE1 7RH Leicester, U.K.;(3) Department of Molecular Biology, University of Edinburgh, EH9 3JR Edinburgh, U.K.;(4) Present address: Department of Biochemistry, University of Leeds, LS2 9JT Leeds, U.K. |