Figure 1

Schematic representation of the membrane with adsorbed PLL. Bulk water is above and below the membrane suspended in an aperture of a Teflon septum. $D_L$, $D_{p1}$, $D_{p2}$, and $D_{\mathrm{PLL}}$ denote the dye diffusion coefficients in the absence of PLL (light orange), in contact with PLL (black lipids), in the distant monolayer of a PLL-covered patch (dark gray lipids), and the PLL diffusion coefficient in the membrane-bound state, respectively. Viscosities $\eta$ are acting at the side surface (blue) of the cylindrical dye molecule (${\eta }_s$), at its bottom surface (${\eta }_e$) (red) and below the adsorbed PLL ($\eta _e{}^0$) (green). Molecules with longer acyl chains (red dye: DilC, blue dye: DioC) may experience a larger interfacial drag than molecules with shorter acyl chains (blue: F2N12S).Reuse & Permissions

Figure 2

Representative autocorrelation curves. Labeled PLL molecules containing 122 lysine residues [${\mathrm{PLL}}_{122}(\mathrm{Atto}488)$] and unlabeled ${\mathrm{PLL}}_{122}$ ($\approx 90\%$) were added in saturating concentrations into the bulk ($>5\mu \mathrm{g}/\mathrm{ml}$) to ensure maximal coverage of the lipid bilayer. (a) In separate experiments, the long-labeled lipid analogues DilC or DioC were incorporated either into the upper leaflet (green or light gray curve) or into the lower leaflet (red or gray curve). Those in the monolayer distant to ${\mathrm{PLL}}_{122}$ (black curve) were much faster than those directly underneath it (red or gray curve). (b) The short-labeled lipid analogue (F2N12S) showed similar diffusion behavior, but at a faster rate. In this case ${\mathrm{PLL}}_{122}$ mobility was significantly slower than F2N12S in the adjacent leaflet.Reuse & Permissions

Figure 3

Dependence of ${\mathrm{PLL}}_{122}$’s diffusion coefficients (black dots) and labeled lipids on ${\mathrm{PLL}}_{122}$ bulk concentration. The subscripts “SM” (red or gray dots) or “OM” (green or light gray dots) denote that diffusion was monitored in the leaflet just beneath PLL or in the distant leaflet, respectively. DilC and DioC were used as lipid labels. For each data point, $5\times 30\sec$ FCS recordings were taken. The buffer contained 25 mM KCl, 10 mM HEPES, and 0.1 mM EDTA ($p\mathrm{H}$ 7).Reuse & Permissions

Figure 4

The effect of PLL size on lipid mobility. PLL-induced slowdown of lipid motion is shown in the adjacent lipid monolayer (red or gray dots) and the opposite lipid monolayer (green or light gray dots). PLL’s diffusion coefficients are shown in black. (a) PLL bulk concentration between 0 and $1\mu \mathrm{g}/\mathrm{ml}$. (b) Saturating PLL bulk concentration ($>5\mu \mathrm{g}/\mathrm{ml}$). Each dot drawn in the graph is an average of $<16$ independent measurements (compare Fig. 2). The error bars are calculated as standard deviations. Data points with missing error bars are taken from single experiments.Reuse & Permissions