| Single-molecule microscopy on model membranes reveals anomalous diffusion. | |
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MedLine Citation:
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PMID: 9251823 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The lateral mobility of lipids in phospholipid membranes has attracted numerous experimental and theoretical studies, inspired by the model of Singer and Nicholson (1972. Science, 175:720-731) and the theoretical description by Saffman and Delbrück (1975. Proc. Natl. Acad. Sci. USA. 72:3111-3113). Fluorescence recovery after photobleaching (FRAP) is used as the standard experimental technique for the study of lateral mobility, yielding an ensemble-averaged diffusion constant. Single-particle tracking (SPT) and the recently developed single-molecule imaging techniques now give access to data on individual displacements of molecules, which can be used for characterization of the mobility in a membrane. Here we present a new type of analysis for tracking data by making use of the probability distribution of square displacements. The potential of this new type of analysis is shown for single-molecule imaging, which was employed to follow the motion of individual fluorescence-labeled lipids in two systems: a fluid-supported phospholipid membrane and a solid polymerstabilized phospholipid monolayer. In the fluid membrane, a high-mobility component characterized by a diffusion constant of 4.4 microns2/s and a low-mobility component characterized by a diffusion constant of 0.07 micron2/s were identified. It is proposed that the latter characterizes the so-called immobile fraction often found in FRAP experiments. In the polymer-stabilized system, diffusion restricted to corrals of 140 nm was directly visualized. Both examples show the potentials of such detailed analysis in combination with single-molecule techniques: with minimal interference with the native structure, inhomogeneities of membrane mobility can be resolved with a spatial resolution of 100 nm, well below the diffraction limit. |
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Authors:
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G J Schütz; H Schindler; T Schmidt |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biophysical journal Volume: 73 ISSN: 0006-3495 ISO Abbreviation: Biophys. J. Publication Date: 1997 Aug |
Date Detail:
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Created Date: 1997-09-29 Completed Date: 1997-09-29 Revised Date: 2010-09-13 |
Medline Journal Info:
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Nlm Unique ID: 0370626 Medline TA: Biophys J Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1073-80 Citation Subset: IM |
Affiliation:
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Institute for Biophysics, University of Linz, Austria. |
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| MeSH Terms | |
Descriptor/Qualifier:
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Diffusion Dimyristoylphosphatidylcholine / chemistry* Fluorescent Dyes Kinetics Lipid Bilayers / chemistry* Liposomes / chemistry* Microscopy, Fluorescence / methods Models, Chemical Molecular Conformation Phosphatidylcholines / chemistry* Phosphatidylethanolamines / chemistry* Rhodamines / chemistry* Sensitivity and Specificity |
| Chemical | |
Reg. No./Substance:
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0/Fluorescent Dyes; 0/Lipid Bilayers; 0/Liposomes; 0/Phosphatidylcholines; 0/Phosphatidylethanolamines; 0/Rhodamines; 0/triethylammonium N-(6-tetramethylrhodaminethiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine; 13699-48-4/Dimyristoylphosphatidylcholine; 4158-89-8/tetramethylrhodamine isothiocyanate; 6753-55-5/1-palmitoyl-2-oleoylphosphatidylcholine |
| Comments/Corrections | |
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