(B) Sterol specificity of the GRAM domain of GRAMD1b (GRAM1b) as assessed via liposome sedimentation assays. Liposomes containing the indicated mole% lipids were incubated with purified GRAM1b proteins as indicated. Bound proteins [pellet, (P)] were separated from the unbound proteins [supernatant, (S)], run on SDS-PAGE and visualized by colloidal blue staining (mean ± SEM, n = 6 independent experiments for liposomes containing only DOPC, n = 3 independent experiments for the rest). DOPC, phosphatidylcholine (1,2-dioleoyl-sn-glycero-3-phosphocholine). 