Fig. 1: Curvature of GUV membranes induced by His-tagged GFP.

Cartoons of lipid bilayers and confocal images of GUVs a in the absence of GFP, that is, for GFP solution concentration X = 0 nM and GFP coverage Γ = 0 μm⁻¹. b For X = 0.78 nM and Γ = 5.4 μm⁻². c For X = 7.8 nM and Γ = 54 μm⁻². In the cartoons, the anchor-lipids (yellow) bind the His-tags of the bulky GFP barrels (multi-colored). These protein barrels have an extension that is comparable to the lipid bilayer thickness of about 4 nm. The average separation of the membrane-bound GFPs is much larger than the bilayer thickness and equal to 136 nm for the right-most cartoon with Γ = 54 μm⁻² (not drawn to scale). In the confocal images, the GUV membranes (red) were doped with 0.1 mol% lipid dye. a The image displays a spherical GUV with vesicle size R_ve, related to the membrane area A via \({R}_{{\rm{ve}}}\equiv \sqrt{A/(4\pi )}=14.5\) μm. c The image shows a dumbbell shape consisting of two spherical membrane segments with radii R₁ = 7.27 μm and R₂ = 0.92 μm. These two segments are connected by a closed membrane neck with neck curvature \({M}_{{\rm{ne}}}=\frac{1}{2}({R}_{1}^{-1}+{R}_{2}^{-1})=0.61\,\) μm⁻¹ (see the “Methods” section, Eq. (4)). All scale bars: 5 μm.