Ultrafast diffusion of a fluorescent cholesterol analog in compartmentalized plasma membranes.
Bottom Line: Surprisingly, in the intact PM, Bdp-Chol diffused at the fastest rate ever found for any molecules in the PM, with a median diffusion coefficient (D) of 3.4 µm²/second, which was ∼10 times greater than that of non-raft phospholipid molecules (0.33 µm²/second), despite Bdp-Chol's probable association with raft domains.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
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.