Figure 1.

The HP1 5΄ domain of 7SK. (A) Sequence of the 5΄-hairpin (HP1) studied in the present structural work. In red, sequence changes made to facilitate production by enzymatic synthesis while keeping the base-pairing scheme (A25G, C26G, G85C, U86C) or crystallization (loop reduction from the original 11 nucleotides to a tetraloop UUCG). (B) Localization of HP1 (squared) in the full-length 7SK model. The 7SK-motif is shown in red. (C and D) HEXIM-binding assays. (C) Native gel showing the complexes (band noted X) formed by titration with HEXIM of the wild-type RNA HP1 (WT) or after loop reduction to UUCG or GAAA (free RNA band noted R). (D) Binding curves from (C) data.