Fig. 3
Known crystal and NMR structures of the PX domains. PX domains with known X-ray crystal or NMR structures are all shown in the orientation using a white cartoon representation. They are grouped according to their phosphoinositide-binding preferences (Fig. 2a). Known ligands including PtdIns3P and SO42− ions are shown in stick representation. Side-chains that are required for coordinating PtdIns3P in that canonical binding site are shown in blue with thick bonds. Shown in magenta are conserved His or Tyr side chain present in the α1 helix, and adjacent basic residues that together form a putative secondary binding site for alternative phosphoinositides. A sequence alignment highlighting these residues is shown in Fig. 4
