1. Department of Bioinformatics, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, 166 10, Czech Republic
2. Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague 2, 128 43, Czech Republic
3. European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Cambridge, UK