1. Department of Biochemistry, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan, Department of Medical Biochemistry and Biophysics, Umeå University, S-901 87 Umeå, Sweden, Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-0034, Japan, Department of Biochemistry, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan, and Department of Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan