Fig. 3: Crystal structures of IP3K-ligand complexes.

A zoom of IP3K-ligand structures showing the ligand recognition site for InsP3 and InsP4 isomers (1–4). At the top of the figure the complexes with substrate InsP3 and product InsP4 properly numbered are shown to facilitate comparison (PDB codes 1w2c and 1w2d respectively). Protein is represented as cartoons showing important residues as sticks (N-lobe in blue, C-lobe in green and IP-lobe in gold), ligands as sticks (carbons in lemon for nucleotide and brown for inositide, oxygens in red, nitrogen in blue and phosphates in orange) and ions and waters as purple and red spheres respectively. Arrows link IP3K-substrate complexes with their related IP3K-product complexes.