Edidin, Michael and Stroynowski, Iwona (1991) Differences between the lateral organization of conventional and inositol phospholipid-anchored membrane proteins. A further definition of micrometer scale membrane domains. Journal of Cell Biology, 112 (6). pp. 1143-1150. ISSN 0021-9525 http://resolver.caltech.edu/CaltechAUTHORS:EDIjcb91
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Plasma membranes of many cells appear to be divided into domains, areas whose composition and function differ from the average for an entire membrane. We have previously used fluorescence photo-bleaching and recovery to demonstrate one type of membrane domain, with dimensions of micrometers (Yechiel, E., and M. Edidin. 1987, J. Cell Biol. 105: 755- 760). The presence of membrane domains is inferred from the dependence of the apparent mobile fraction of labeled molecules on the size of the membrane area probed. We now find that by this definition classical class I MHC molecules, H-2Db, are concentrated in domains in the membranes of K78-2 hepatoma cells, while the nonclassical class I- related molecules, Qa-2, are free to pass the boundaries of these domains. The two proteins are highly homologous but differ in their mode of anchorage to the membrane lipid bilayer. H-2Db is anchored by a transmembrane peptide, while Qa-2 is anchored by a glycosylphosphatidylinositol (GPI) anchor. A mutant class I protein with its external portion derived from Qa-2 but with transmembrane and cytoplasmic sequences from a classical class I molecule shows a dependence of its mobile fraction on the area of membrane probed, while a mutant whose external portions are a mixture of classical and nonclassical class I sequences, GPI-linked to the bilayer, does not show this dependence and hence by our definition is not restricted to membrane domains.
|Additional Information:||Copyright © 1991 by The Rockefeller University Press. Received for publication 1 August 1990 and in revised form 1 December 1990. We thank Mrs. K. Blackburn and Mrs. Taiyin Wei for technical assistance. This work was supported by National Institutes of Health grants AI14584 (M. Edidin) and AI17565 (I. Stroynowski).|
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|Deposited On:||30 Jan 2007|
|Last Modified:||26 Dec 2012 09:30|
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