Modes of Diffusion of Cholera Toxin Bound to GM1 on Live Cell Membrane by Image Mean Square Displacement Analysis

Author(s)
Moens, Pierre
Digman, Michelle
Gratton, Enrico
Publication Date
2015
Abstract
The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to -1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates.
Citation
Biophysical Journal, 108(6), p. 1448-1458
ISSN
1542-0086
0006-3495
Link
Publisher
Elsevier Inc
Title
Modes of Diffusion of Cholera Toxin Bound to GM1 on Live Cell Membrane by Image Mean Square Displacement Analysis
Type of document
Journal Article
Entity Type
Publication

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