Figure 6.

Cristae-like membrane invaginations. (A) Modulation of local pH gradient at membrane level of a cardiolipin containing vesicle induces dynamic cristae-like membrane invaginations. GUV is made of PC/PE/CL 60:30:10 mol/mol in buffer at pH 8. The local delivery of HCl (100 mM pH 1.6), which lowers the local pH, is carried out by a micropipette (its position is pointed by the arrow in frame t = 0 s).The induced membrane invagination (frame 22.8 s) is completely reversible (frames 38.7–66.4) as far as the acid delivery is stopped. Geometrical features of the tubular invagination calculated from the model as a function of the area reduction factor $\lambda$ that is controlled by the acid delivery (the lower $\lambda$, the stronger acid effect): (B) Radius of the tube normalized by the radius of the initial vesicle. (C) Aspect ratio of the tube. Both are given for three experimentally relevant values of the reduced volume v of the initial vesicle. Two experimental illustrations are given for $\nu$ = 0.85 and 0.75 and L/(2r) ratios ∼40 and 14, respectively. Reproduced with permission from Khalifat et al. [86], Biophys. J.; published by Elsevier, 2008.