Interactions between dsRBDs 3 and 4 of hStau1 and ARF1 SBS. Interactions between dsRBDs 3 and 4 of hStau1 and ARF1 SBS. (A) Close-up view of hStau1 dsRBD3A (left), dsRBD3B (middle), and dsRBD4 (right) in complex with ARF1 SBS. Residues making contact with the RNA are shown as sticks and labeled; residues making base contacts within the minor groove of the dsRNA are marked in bold; residues mutated in (B) are highlighted in red. (B) The scheme on the left depicts the three dsRBD regions interacting with dsRNA: helix α1 (region 1) and loop β1–β2 (region 2) bind two subsequent minor grooves, whereas the N-terminal half of helix α2 (region 3) contacts the intervening major groove. Right: Kd values determined by FA, as in Fig 1D and E. Mutated residues, in region 2 and 3, are labeled in red in (A). 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.