Figure 6.

(A) Overlay of the proposed catalytic residues for INPP5B–BiPh(3,3′,4,4′,5,5′)P₆ (green), INPP5B–Bz(1,2,4,5)P₄ (yellow), INPP5B–PtdIns4P (dark blue) SHIP2–BiPh(2,3′,4,5′,6)P₅ (light blue), and SPsynaptojanin–Ins(1,4)P₂ (red) complexes. Numbering is for the INPP5B enzyme. (B) Overlay of inorganic phosphate from the INPP5B–BiPh(3,3′,4,4′,5,5′)P₆ complex structure with water molecules from INPP5B–PtdIns4P, SPsynaptojanin-Ins(1,4)P₂ apo-SPsynaptojanin, and SHIP2–BiPh(2,3,′4,5′,6)P₅ structures. Only the catalytic residues surrounding the water molecule are shown for clarity. The Mg²⁺ from the INPP5B–BiPh(3,3′,4,4′,5,5′)P₆ complex structure is shown as a green sphere, and the PtdIns4P from the INPP5B complex is shown in blue. (C) Overlay of the phosphate anion and co-ordinating residues from the INPP5B–BiPh(3,3′,4,4′,5,5′)P₆ complex with the ligand and the INPP5B–PtdIns4P complex. (D) Overlay of the active site regions of INPP5B–BiPh(3,3′,4,4′,5,5′)P₆ (gray carbons; Mg²⁺ as a green sphere; inorganic phosphate in green) AP endonuclease–DNA (pink carbons; Mn²⁺ as a purple sphere; DNA shown as a cartoon with the cleaved sugar–phosphate groups shown as sticks). Residue numbering is for INPP5B with AP endonuclease in parentheses.