Figure 2.

Ash2L_PHD is an atypical PHD finger. (A) Superimposition of Ash2L_PHD (cyan), PHF8_PHD (marine) and BPTF_PHD (yellow). There are two zinc ions in the PHF8_PHD structure (grey), but only one zinc ion in Ash2L_PHD (orange). (B) Structure-based sequence alignment of Ash2L_PHD with four PHD fingers that share high structural similarity. The conserved zinc-binding residues are highlighted in orange, the absent zinc-binding residues in pink and the absent aromatic cage residues in grey. (C) Structural superimposition of Ash2L_PHD (cyan) and the PHF8_PHD–H3 peptide complex (marine). H3 peptide is shown in sticks (grey). The carboxy-terminal wing 2 from Ash2L_WH is shown in orange. (D) The R14 of Ash2L (magenta) and the K4 of H3 (green) occupy the same pocket surrounded by aromatic residues. WH, winged helix; Zn, zinc.