Fig. 3. The P-Rex1 IP4P domain is a structural homolog of the Legionella phosphatase SidF.

(A) IP4P domain superimposed on SidF (residues 183 to 743) in complex with PI(3,4)P₂. For the figure, residues 1579 to 1589 of P-Rex1 were aligned with residues 641 to 651 of SidF. (B) Residues in P-Rex1 (top) compared with catalytic residues in SidF (bottom). A likely counterpart of Asp⁶⁵⁰ in SidF is Asp¹⁶³⁸ on the TI loop of P-Rex1. Canonical phosphatase loops are indicated in yellow. A loop from Gβ is shown to indicate its proximity. (C) Surface representation colored by electrostatic potential of the structures shown in (B).