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. 2016 Nov 23;16(1):100–112. doi: 10.1080/15384101.2016.1255384

Figure 3.

Figure 3.

U4/U6 binding by Brr2 and possible inhibitory mechanisms. (A) yBrr2-Jab1 bound to U4/U6 as seen in the cryo-EM structure of a yeast U4/U6•U5 tri-snRNP (PDB ID 5GAO).27 (B) Structure of the isolated yBrr2FL-Jab1 complex with portions of U4/U6, obtained by superimposition with the structure in (A) according to the NCs of the Brr2 subunits. (C) The NC-clamp and part of the PWI domain of the NTR bind U4/U6 stem II in the yeast U4/U6•U5 tri-snRNP. (D) The HLH domain of the NC contacts the U4 3′-SL in the yeast U4/U6•U5 tri-snRNP. (E) In isolated yBrr2FL-Jab1, the plug domain of the NTR sterically hinders accommodation of the stem I portion of U4/U6 between the RecA2 and HB domains of the NC. (F) In isolated yBrr2FL-Jab1, the Jab1 C-terminal tail binds along and hinders opening of the HB and RecA2 domains to accommodate RNA and occupies part of the tunnel that accommodates the ss region of U4 snRNA neighboring U4/U6 stem I during U4/U6 unwinding. U4 snRNA – brown; U6 snRNA – orange.