FAM92A1 binds the mitochondrial membrane and induces a high degree of positive membrane curvature. (A) Schematic diagram of his-tagged full-length FAM92A1, its BAR domain, and FAM92A1Δ1–40aa. The putative cleavage site is indicated with a red arrow. (B) The BAR domain of FAM92A1 mainly forms dimers in solution, in equilibrium with minor higher-molecular-weight oligomers as determined by multiangle light scattering. (C) Vesicle cosedimentation assay for the interaction of FAM92A1 with mitochondrial model membranes. (D) Vesicle cosedimentation assay for lipid-binding specificity of FAM92A1. PI(4,5)P2 was included as the same amount as in vivo cardiolipin quantity in the MIM. (E) Changes in DPH anisotropy upon membrane association of the full-length FAM92A1 and FAM92A1Δ1–40aa. (F) Membrane tubulation of unilamellar vesicles with a lipid composition of the MIM by full-length FAM92A1, its BAR domain, and FAM92A1Δ1–40aa. (G) Quantification of vesicles with tubules in F. At least 300 vesicles were used for quantification. (H) Column scatter graph for quantifying the tubule diameter in F. At least 200 membrane tubules were used for analysis. (I) The untagged full-length FAM92A1, its BAR domain, and FAM92A1Δ1–40aa induced membrane tubulation in giant unilamellar vesicles (GUVs) with a lipid composition of the MIM. The arrows indicate membrane tubules. (J) Quantification of giant vesicles with tubules in I. Bars, 2.5 µm. *, P ≤ 0.05; **, P ≤ 0.001; ***, P ≤ 0.001, Student's t test.
