Fig. 3: The putative pore of hXPR1.
From: The identification of XPR1 as a voltage- and phosphate-activated phosphate-permeable ion channel
a (left) The solvent-accessible surface of the hXPR1 TMD colored by ±5 kT/e electrostatic potential calculated using APBS62. The secondary structures of TM1-4 are shown in gray and TM5-10 in light cyan. The positively charged vestibule formed at the center of the barrel-shaped helical bundle of TM5-10 is boxed in red. Two solid black lines indicate the membrane boundary. (right) The electrostatic surface–potential map depicts the same vestibule alone, viewed orthogonally from the extracellular space. b The putative pore location in hXPR1 inside the 6-helix barrel colored light cyan, and the pore pathway is depicted as a purple mesh. The residues on the TM5-10 that are conserved among hXPR1, atPHO1, and scSYG1 are colored in dark green. c Pore radius along the z coordinate. d, e Detailed view of the green-colored conserved pore-lining residues shown in stick model on TM5, 7, and 9 (d), and TM6, 8, and 10 (e).
