Fig 1.
Structure of cholesterol and cholesterol-rich lipid membranes.
(A) Structure of cholesterol (B) Illustration of cholesterol (C) Lipid membrane of GUV and (D) Cholesterol-rich lipid membrane.
Fig 2.
Effects of cholesterol on the size distribution of GUVs containing neutral membranes.
(A) and (B) show a phase contrast image and a size distribution histogram of DOPC/chol (100/0)-GUVs, respectively. (C) and (D) show a phase contrast image and a size distribution histogram of DOPC/chol (71/29)-GUVs, respectively. The bar in the images corresponds to 50 μm. N is the number of measured GUVs in each independent experiment. The blue lines show the best fitting curves of Eq 1. The parameters in (B) are μ = 2.25, σ = 0.49, and in (D) are μ = 2.63, σ = 0.39. The values of the coefficient of determination, R2, are obtained 0.91 in (B) and 0.95 in (D) from the fitted (blue) curves. The red lines show the best fitting theoretical curves corresponding to the Eq 7. The fitting parameters in (B) are Kben = 19.0 kBT, Dfreq = 6.4 μm, L = 3535, and in (D) are Kben = 28.5 kBT, Dfreq = 9.1 μm and L = 4230. The values of R2 in (B) and (D) are obtained 0.92 and 0.69, respectively from the fitted (red) curves.
Fig 3.
Effects of cholesterol on the size distribution of charged GUVs.
(A) and (B) show a phase contrast image and a size distribution histogram of DOPG/DOPC/chol (46/39/15)-GUVs, respectively. (C) and (D) show a phase contrast image and a size distribution histogram for DOPG/DOPC/chol (40/20/40)-GUVs, respectively. The bar in the images corresponds to 50 μm. N is the number of measured GUVs in each independent experiment. The blue lines show the best fitting theoretical curves corresponding to Eq 1. The parameters in (B) are μ = 2.66, σ = 0.42, and in (D) are μ = 2.74, σ = 0.60. The values of R2 are obtained 0.88 in (B) and 0.84 in (D) for the fitted (blue) curves. The red lines show the theoretical curves of Eq 7. The parameters in (B) are Kben = 26.6 kBT, Dfreq = 8.6 μm, L = 3700, and in (D) are Kben = 36.8 kBT, Dfreq = 9.5 μm and L = 3600. The values of R2 in (B) and (D) are obtained 0.76 and 0.86, respectively for the fitted (red) curves.
Fig 4.
The cholesterol concentration dependent average size of DOPC/chol-GUVs and DOPG/DOPC/chol-GUVs.
Average values and standard errors of the size for each membrane were obtained from 12–16 independent experiments using 350 GUVs in each experiment. The solid lines show the theoretical curve corresponding to the Eqs 12, 13 and 14. The fitting parameters for DOPC/chol-GUVs are DfreqPC = 15.8 μm, KDOPC = 18.0 kBT and η = 0.45 kBT and for DOPG/DOPC/chol-GUVs are DfreqPC = 18.9 μm, KDOPC = 18.0 kBT, η = 0.33 kBT and γ = 2.9 kBT/mM3/2. The values of R2 are obtained 0.99 and 0.62 for DOPC/chol-GUVs and DOPG/DOPC/chol-GUVs, respectively.
Table 1.
A summary of the data for bending modulus of cholesterol containing membranes.
Fig 5.
Relationship between the average size and the of cholesterol containing neutral and charged membranes.
Average values and standard errors are determined from 12–16 independent experiments.