[1] European Mol Biol Lab, Heidelberg, Germany
[2] Scripps Res Inst, La Jolla, CA 92037 USA
[3] Goethe Univ Frankfurt, Frankfurt, Germany
[4] Univ Strasbourg, CNRS, Inst Biol Mol & Cellulaire, Strasbourg, France
[5] European Bioinformat Inst, Cambridge, England
[6] Inst Pasteur, Paris, France
[7] Univ London Birkbeck Coll, Inst Struct & Mol Biol, London WC1E 7HX, England
[8] HITS, Heidelberg, Germany