G–C addition to a synthetic dsRNA substrate restores affinity of binding. G–C addition to a synthetic dsRNA substrate restores affinity of binding. (A) Schematic representation of the ARF1 SBS and of the designed synthetic duplexes. Watson–Crick base pairs are labeled with an hyphen in different colors with C–G in red and U–A in gray, whereas wobble pairs with a yellow dot. Below each RNA, the Kd of binding of hStau1 FL is indicated. Boxes highlight base contacts by dsRBD3 (in blue) and dsRBD4 (in cyan). (B)Kd values determined by fluorescence anisotropy (FA), using 5ʹ-fluorescein-labeled dsRNAs. The recombinantly purified hStau1 FL is indicated in the schematic above. The graphs show mean Kd (bars), standard deviation (black lines), and Kd values obtained in each independent experiment (black dots). Mean Kd ± SD, in nM, and number of independent measurements (n) are indicated on the right. Daniela Lazzaretti et al. LSA 2018;1:e201800187 © 2018 Crown copyright. The government of Australia, Canada, or the UK ("the Crown") owns the copyright interests of authors who are government employees. The Crown Copyright is not transferable.