1. 1Division of Biochemistry and Molecular Biology, John Curtin School of Medical Research, The Australian National University, G.P.O. Box 334, Canberra City, ACT 2601, Australia
2. 2Department of Natural Science, Kyoto Women's University, 35 Kitahiyoshi-cho, Imakumano, Higashiyama-ku, Kyoto 605, Japan