[1] Univ Munich, DZNE, D-80336 Munich, Germany
[2] Univ Munich, Adolf Butenandt Inst, D-80336 Munich, Germany
[3] DESY, Max Planck Unit Struct Mol Biol, D-2000 Hamburg, Germany
[4] AstraZeneca Res & Dev, Sodertalje, Sweden
[5] Helmholtz Zentrum Munchen, Inst Dev Genet, Neuherberg, Germany