Figure 1. PIP5K1A structure.

(a,b) Crystal structure of zebrafish PIP5K1A kinase catalytic domain and its comparison with that of PKA. The N- and C-terminal segments outside the kinase core domain are omitted to better illustrate the protein kinase fold. In both panels, the N-lobe is coloured grey and the C-lobe is yellow. The ‘C helix' is highlighted in red. The substructure harbouring the lipid kinase's DLKGS motif is highlighted in blue. The N-terminal secondary structures found only in phosphatidylinositol phosphate kinases are shown in pink. The structure C-terminal to PKA's αF, missing in the phosphatidylinositol phosphate kinases, is coloured green. The disordered regions are indicated by dotted lines. (c,d) The DLKGS motifs of zPIP5K1A and PIP4K2B. The substructure (blue) harbouring the DLKGS motif reveals differences between zPIP5K1A (c) PIP4K2B (d). The C-lobe of the kinase is coloured yellow. Dashed lines represent potential hydrogen bonds.