(C) DHE transfer between liposomes by purified GRAMD1b proteins. Left: Representative time course of DHE transfer from LPM to LER mediated by either wild-type GRAMD1b proteins (WT), mutant GRAMD1b G187L proteins (G187L), or buffer alone as indicated. Methyl-β-cyclodextrin (MCD) at 1 mM was used to determine DHE equilibration. Experiments and data analysis were performed as in Fig 4. Right: Values of DHE transfer rate of wild-type GRAMD1b (WT) and mutant GRAMD1b (G187L), as estimated by the FRET-based lipid transfer assay (mean ± SEM, n = 3 independent experiments; two-tailed unpaired Student's t-test, **P < 0.0014). 