Institution: | *Institute of Biology–Genetics, Freie Universität Berlin, 14195 Berlin, Germany, †George Williams Hooper Foundation, University of California, San Francisco, California 94143-0552, ‡Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143 and §Institute of Biology–Cytogenetics, Humboldt University Berlin, 10115 Berlin, Germany |