Biopolis Dresden Imaging Platform

Plasma membranes are poised for activation of raft phase coalescence at physiological temperature.

Lingwood D, Ries J, Schwille P, Simons K

Cell membranes are not randomly organized, but rather are populated by fluctuating nanoassemblies of increased translational order termed lipid rafts. This lateral heterogeneity can be biophysically extended because cooling formaldehyde-isolated plasma membrane preparations results in separation into phases similar to the liquid-ordered (Lo) and liquid-disordered (Ld) states seen in model membrane systems [Baumgart T, et al. (2007) Proc Natl Acad Sci USA 104:3165-3170]. In this work we demonstrate that raft clustering, i.e., amplifying underlying raft-based connectivity to a larger scale, makes an analogous capacity accessible at 37 degrees C. In plasma membranes at this temperature, cholera toxin-mediated cross-linking of the raft ganglioside GM1 induced the sterol-dependent emergence of a slower diffusing micrometer-scale phase that was enriched in cholesterol and selectively reorganized the lateral distribution of membrane proteins. Although parallels can be drawn, we argue that this raft coalescence in a complex biological matrix cannot be explained by only those interactions that define Lo formation in model membranes. Under this light, our induction of raft-phase separation suggests that plasma membrane composition is poised for selective and functional raft clustering at physiologically relevant temperature.

Fig.3 taken from Lingwood et al, 2008.
  • Proc. Natl. Acad. Sci. U.S.A. 2008 Jul 22;105(29):10005-10
  • 2008
  • Biophysics
  • 18621689
  • PubMed

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