Fig. 3: Structural changes in Xkr4.

a, b The cryoEM structures of hXkr4 and hXkr8 (PDBID: 8XEJ), shown in cylindrical cartoon representations, are aligned on their respective CD domains (wheat for hXkr4 and cyan for hXkr8). The pseudo-symmetry axis (dashed vertical line, panel a) and angle of rotation of the ND of hXkr4 (pale blue) relative to the ND of hXkr8 (pale green) is viewed from the plane of the membrane (a) or from the extracellular solution (b). The C-terminal helix of hXkr8 is colored in pink. c The distance between the Cα atoms (maroon spheres) of L147 and S158 on TM2 and of G402W on TM6 and V436 on IH3 is shown (dashed lines). d Forward (α) and reverse (β) scrambling rate constants of WT (n = 9), L147W/G402W (n = 9), S158W/V436W (n = 9) hXkr4 reconstituted in DO-mix liposomes. Bars are averages for α (black) and β (gray) (N ≥ 3), error bars are S. Dev., and red circles are values from individual repeats whose values are reported in the Source Data Files. Alignment of the ND (e) and CD (f) repeats of hXkr4. Colors as in (a, b). Arrows denote direction of movement of the helices from hXkr8 to hXkr4. The charged residues in the ND of hXkr4 (hXkr8), D125 (D26), D129 (D30), E313 (E141), and Y122 (F23) are shown in stick representation and colored in yellow CPK (hXkr4) or pink CPK (hXkr8). Inset of (e) shows a close-up view of these residues.