Cholesterol depletion induces solid-like regions in the plasma membrane.
Glycosylphosphatidylinositol-linked and transmembrane major histocompatibility complex (MHC) class II I-E(k) proteins, as well as N-(6-tetramethylrhodaminethiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (Tritc-DHPE), are used as probes to determine the effect of cholesterol concentration on the organization of the plasma membrane at temperatures in the range 22 degrees C-42 degrees C. Cholesterol depletion caused a decrease in the diffusion coefficients for the MHC II proteins and also for a slow fraction of the Tritc-DHPE population. At 37 degrees C, reduction of the total cell cholesterol concentration results in a smaller suppression of the translational diffusion for I-E(k) proteins (twofold) than was observed in earlier work at 22 degrees C (five sevenfold) Vrljic, M., S. Y. Nishimura, W. E. Moerner, and H. M. McConnell. 2005. Biophys. J. 88:334-347. At 37 degrees C, the diffusion of both I-E(k) proteins is Brownian (0.9 < alpha-parameter < 1.1). More than 99% of the protein population diffuses homogeneously when imaged at 65 frames per s. As the temperature is raised from 22 degrees C to 42 degrees C, a change in activation energy is seen at approximately 35 degrees C in the Arrhenius plots. Cytoskeletal effects appear to be minimal. These results are consistent with a previously described model of solid-like domain formation in the plasma membrane.
Nishimura
Stefanie Y
SY
Department of Chemistry, Molecular and Cellular Physiology, and Biophysics Program, Stanford University, Stanford, California 94305-5080, USA. snishimu@stanford.edu
Vrljic
Marija
M
Klein
Lawrence O
LO
McConnell
Harden M
HM
Moerner
W E
WE
D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D006224:Cricetinae; D003599:Cytoskeleton / Q000378:metabolism; D004058:Diffusion; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D000949:Histocompatibility Antigens Class II / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D008055:Lipids / Q000737:chemistry; D051379:Mice; D015739:Nocodazole / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014162:Transfection
D017261:Glycosylphosphatidylinositols; D000949:Histocompatibility Antigens Class II; D008055:Lipids; D011506:Proteins; D002784:Cholesterol; D015739:Nocodazole