1. National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD 20892.
2. Laboratory of Biochemistry and Molecular Biology, Rockefeller University, NY 10021.
3. Laboratory of Neurochemistry, NIDCD, National Institutes of Health, Bethesda, MD 20892.
4. Institute of Applied Microbiology, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.