Extended Data Fig. 8: Comparison of structural elements occupying the cleft of Pol I, II, and III.
From: Structures of transcription preinitiation complex engaged with the +1 nucleosome
a. Pol I and Pol III contain elements that can occupy the active center cleft at a location corresponding to that observed for the Rpb6 NTT in Pol II (Extended Data Fig. 4). These elements are referred to as the expander or DNA-mimicking loop of A190 in yeast Pol I (PDB code: 4C3H)31, and as the C-terminal tail of RPC7 (C31 in yeast) in human Pol III (PDB code: 7D59)32. b. Superposition of cleft elements in Pol I, Pol II and Pol III. The bridge helix and the catalytic magnesium ion in the active site are indicated.
