Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan, Institute for Bioinformatics Research and Development, Japan Science and Technology Agency, 5-3 Yonbancho, Chiyoda, Tokyo 102-8666, Japan, Graduate School of Life Science, University of Hyogo, Koto, Kamigori, Hyogo 678-1297, Japan, The RIKEN SPring-8 Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5248, Japan, and Faculty of Engineering, Yokohama National University, Hodogaya-ku, Yokohama 240-8501, Japan (At 2008-08-15)