Figure 7. Transient (∼15-ms) molecular-scale colocalization of two 594neg-SM molecules at raft-related structures in the CHO-K1-cell PM at 37°C, recorded at a 4-ms resolution, which was undetectable in artificial lipid bilayers. (A) Typical image sequence of two diffusing 594neg-SM molecules (red and green arrowheads before colocalization; blue and brown arrowheads after colocalization) undergoing transient colocalization and codiffusion (orange arrowheads). The number in the upper-left corner in each image indicates the number of frames. Trajectories are shown in a twofold magnified scale (displayed intermittently). The initial points of the trajectories are shown by closed circles. The end points of the trajectory shown by the arrowheads matched the fluorescent spots indicated by arrowheads in the image right above the trajectory. The green, red, orange, dark-blue, and brown colors indicate molecules (colors matched with those in the arrows in the images) before, during, and after colocalization, respectively. (B) Duration distributions for individual homo-colocalization events for single molecules of 594neg-SM (under various conditions), 594neg-DOPC, and 594neg-DSPC. All of the distributions could be fitted by single-exponential decay functions, but because the short molecular interaction lifetimes, the durations for incidental colocalization and those for colocalization including the molecular-scale interaction could not be separated. The decay time constants are shown in the boxes. The number of the observed colocalization events were 260, 223, 237, 220, 206, and 243 from left to right. (C) The duration distributions of individual homo-colocalization events for single 594neg-SM and 594neg-DOPC molecules in artificial planar bilayers in Lα or Lo phase observed at a 4-ms time resolution, showing that the homo-colocalization of 594neg-SM, which was prolonged from that of 594neg-DOPC, in the cellular PM (48 vs. 33 ms), did not occur in either Lo or Lα artificial planar lipid bilayers. For Lα membranes, DMPC bilayers (30°C) and DOPC bilayers (25°C) were used, whereas for Lo membranes, DMPC-cholesterol (65:35 mol/mol; 20°C) and DPPC-cholesterol (65:35 mol/mol; 37°C) were used. The numbers of the observed colocalization events were 223, 225, 206, and 210 from left to right in the top row and 221, 243, 227, and 231 from left to right in the bottom row.
Figure 7.

Transient (∼15-ms) molecular-scale colocalization of two 594neg-SM molecules at raft-related structures in the CHO-K1-cell PM at 37°C, recorded at a 4-ms resolution, which was undetectable in artificial lipid bilayers. (A) Typical image sequence of two diffusing 594neg-SM molecules (red and green arrowheads before colocalization; blue and brown arrowheads after colocalization) undergoing transient colocalization and codiffusion (orange arrowheads). The number in the upper-left corner in each image indicates the number of frames. Trajectories are shown in a twofold magnified scale (displayed intermittently). The initial points of the trajectories are shown by closed circles. The end points of the trajectory shown by the arrowheads matched the fluorescent spots indicated by arrowheads in the image right above the trajectory. The green, red, orange, dark-blue, and brown colors indicate molecules (colors matched with those in the arrows in the images) before, during, and after colocalization, respectively. (B) Duration distributions for individual homo-colocalization events for single molecules of 594neg-SM (under various conditions), 594neg-DOPC, and 594neg-DSPC. All of the distributions could be fitted by single-exponential decay functions, but because the short molecular interaction lifetimes, the durations for incidental colocalization and those for colocalization including the molecular-scale interaction could not be separated. The decay time constants are shown in the boxes. The number of the observed colocalization events were 260, 223, 237, 220, 206, and 243 from left to right. (C) The duration distributions of individual homo-colocalization events for single 594neg-SM and 594neg-DOPC molecules in artificial planar bilayers in Lα or Lo phase observed at a 4-ms time resolution, showing that the homo-colocalization of 594neg-SM, which was prolonged from that of 594neg-DOPC, in the cellular PM (48 vs. 33 ms), did not occur in either Lo or Lα artificial planar lipid bilayers. For Lα membranes, DMPC bilayers (30°C) and DOPC bilayers (25°C) were used, whereas for Lo membranes, DMPC-cholesterol (65:35 mol/mol; 20°C) and DPPC-cholesterol (65:35 mol/mol; 37°C) were used. The numbers of the observed colocalization events were 223, 225, 206, and 210 from left to right in the top row and 221, 243, 227, and 231 from left to right in the bottom row.

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal