Structural Informatics Group, Department of Biological Structure, University of Washington, Seattle, USA. eider@u.washington.edu|Structural Informatics Group, Department of Biological Structure, University of Washington, Seattle, USA. eider@u.washington.edu|Structural Informatics Group, Department of Biological Structure, University of Washington, Seattle, USA. eider@u.washington.edu|Structural Informatics Group, Department of Biological Structure, University of Washington, Seattle, USA. eider@u.washington.edu