Fig. 2. Structure of the kinase domain of human PPIP5K2.

A is a graphical depiction of the modular format of PPIP5K2; the numbering of the amino acid residues depicts where the domains are considered to begin and finish. B, Ribbon diagram of residues 37-366 of PPIP5K2^KD. The αβα domain (residues 42–124 and 330–366) is shown in yellow. The two antiparallel β-sheet clusters of the ATP-grasp domain are colored green (residues 125–148 and 244–329) and blue (residues 149–243). Shown in stick models are 5-InsP₇ and AMP-PNP. C, Active site of PPIP5K2 ^KD. Shown in green are residues that make polar contacts with substrates. 5-InsP₇ is shown with grey carbon and orange and red phosphate groups, while InsP₆ is slate-colored. Carbon atoms on the inositol ring are numbered. The interactions of Lys214 with 5-InsP₇ are highlighted by dashed yellow lines. The sky blue and purple spheres represent the magnesium atoms; The purple magnesium atomss (Mg1 and Mg2) were catalytically relevant. Mg5 was not present in the PPIP5K2^KD–Ins_P6 complex. See (Wang et al., 2012) for full details. D, Electrostatic surface representation of the inositol phosphate substrate binding pocket of PPIP5K2^KD.