Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA and RCSB Protein Data Bank, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA and RCSB Protein Data Bank, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA.|Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA and RCSB Protein Data Bank, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA and RCSB Protein Data Bank, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA.|Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA and RCSB Protein Data Bank, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA.