1. Department of Structural Biology and Biomolecular Engineering, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3‐1 Tanabe‐dori, Mizuho‐ku Nagoya 467‐8603 Japan
2. Genomic Sciences Center, RIKEN Yokohama Institute, 1‐7‐29 Suehiro‐cho, Tsurumi‐ku Yokohama 230‐0045 Japan
3. Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku Tokyo 113‐0033 Japan
4. Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University Sapporo 060‐0812 Japan
5. Department of Neurology, School of Medicine, Juntendo University, 2‐1‐1 Hongo, Bunkyo‐ku Tokyo 113‐0033 Japan
6. Department of Molecular Oncology, Tokyo Metropolitan Institute of Medical Science, 3‐18‐22 Honkomagome, Bunkyo‐ku Tokyo 113‐8613 Japan