Department of Biochemistry and Biophysics, School of Medicine, Gifu University, 40 Tsukasa-machi, Gifu 500-8705, Japan, Department of Molecular Science, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan, and Departments of Neurology, Biochemistry and Biophysics, and Pharmaceutical Chemistry and Institute for Neurodegenerative Diseases, University of California, San Francisco, California 94946-0446 (At 2002-09-18)