1. Faculty of Science and Engineering, Tokyo University of Science, Yamaguchi, Daigaku Dori, Onoda 756-0884, Japan, Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan, Department of Biochemistry, Wayne State University, Detroit, Michigan 48201, and Department of Physiology and Biophysics, University of California, Irvine, California 92717