1. Bioinformatics Group, Department of Computer Science, University of Freiburg, Freiburg, Germany
2. Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
3. Bioinformatics and Computational Biology Research Group, University of Vienna, Vienna, Austria
4. Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg, Germany
5. Bioinformatics Group, Department of Computer Science, University of Leipzig, D-04107 Leipzig, Germany
6. Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany