Ultrafast diffusion of a fluorescent cholesterol analog in compartmentalized plasma membranes.
Bottom Line: In the blebbed PM, where actin filaments were largely depleted, Bdp-Chol and Cy3-conjugated dioleoylphosphatidylethanolamine (Cy3-DOPE) diffused at comparable Ds (medians = 5.8 and 6.2 µm²/second, respectively), indicating that the actin-based membrane skeleton reduces the D of Bdp-Chol only by a factor of ∼2 from that in the blebbed PM, whereas it reduces the D of Cy3-DOPE by a factor of ∼20.These results are consistent with the previously proposed model, in which the PM is compartmentalized by the actin-based membrane-skeleton fence and its associated transmembrane picket proteins for the macroscopic diffusion of all of the membrane molecules, and suggest that the probability of Bdp-Chol passing through the compartment boundaries, once it enters the boundary, is ∼10× greater than that of Cy3-DOPE.Since the compartment sizes are greater than those of the putative raft domains, we conclude that raft domains coexist with membrane-skeleton-induced compartments and are contained within them.
Affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS) and Institute for Frontier Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan.Show MeSH
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Mentions: The treatment with latrunculin-B induced ∼2-fold increases in the compartment size (evaluated by ultrafast single gold-particle tracking using Gold-PEs; Figure 8, left column, Table4). In contrast, as described in the previous subsection, it modestly increased the DeffMACRO values of Cy3-PEs by a factor of ∼1.2 (Table3).
Affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS) and Institute for Frontier Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan.