1. Department of Life Science, Faculty of Science, Himeji Institute of Technology, Kamigoori-cho, Akou-gun, Hyogo 678-1297, Japan, Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan, and Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan