Figure 6.

Relative Orientations of Inositol Phosphate Analogs in the Second Ligand-Binding Site of PPIP5K2^KD

Data for ligand orientation in the second binding site were obtained as described in Figure 5. Analogs are depicted as stick models. Atoms are blue for nitrogen, red for oxygen, and orange for phosphorus.

(A) Superimposition of 5-PA-InsP₅ (1; carbons in gray) and 2-O-Bn-5-PA-InsP₄ (2; carbons in cyan).

(B and C) Superimposition of 2,5-di-O-Bn-InsP₄ (10; carbons in green) and 2-O-Bn-5-PA-InsP₄ (2; carbons in cyan). Arrows in (B) emphasize spatial separation, and (C) includes details of ligand interactions with neighboring amino acid residues.

(D and E) illustrate that transfer of 5-PA-InsP₅ (1) between the two sites involves a lateral migration of 7 Å, a ring flip, and a rotation of ∼100°. Atoms are blue for nitrogen, red for oxygen, orange for phosphorus, and gray for carbon. The inositol ring is numbered.