1. Institute of Biochemistry and Biotechnology and Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg , Kurt-Mothes-Strasse 3a , 06120 Halle , Germany
2. RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute , 1050 Boyles Street , Frederick , MD 21702, USA
3. Heidelberg University Biochemistry Center (BZH) , Im Neuenheimer Feld 328 , 69120 Heidelberg , Germany