1. Department of Molecular Biology, Genentech, Inc., South San Francisco 94080.
2. Department of Immunology Research and Assay Technology, Genentech, Inc., South San Francisco, CA 94080.
3. National Cardiovascular Center Research Institute, Fujishirodai, Suita, Osaka 565, Japan.
4. Department of Biochemistry, Miyazaki Medical College, Kihara, Kiyotake, Miyazaki 889-16, Japan