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© The Rockefeller University Press, 0021-9525/2001/9/905-b $5.00
The Journal of Cell Biology, Volume 154, Number 5, September 3, 2001 905-b-905

Rafts to the front; rafts to the rear

GM3 (red) and GM1 (green) at the opposite ends of a T cell. Mañes/NAS

Tcells assemble different rafts at the front and rear of the cell as they gear up to move. This is the conclusion of Santos Mañes (Universidad Autónoma de Madrid, Spain) and colleagues, who believe that the distinct rafts help T cells to do two very different things at the front and back of the cell.

Mañes concentrated on two gangliosides called GM1 and GM3—both markers for rafts and, in fibroblasts, both located at the leading edge of the moving cell. In T cells, however, Mañes found that GM3 was at the front of the cell, whereas GM1 was at the back.

The different segregation of the gangliosides and associated proteins makes sense, based on the biology of the two cell types. Fibroblasts grip tightly to their substrate as they crawl forward, and therefore have most of their cell–cell adhesion proteins at the front of the cell. The back of a fibroblast is essentially a passive tail.

By contrast, T cells skim over the surface, and have little need for cell–cell adhesion at their front end. The back of a T cell, the so-called uropod, recruits bystander cells using intercellular adhesion molecules (ICAMs). It is this need to act as a bipolar sensor that distinguishes T cells.

The differential localization of GM1 and GM3 requires an intact actin cytoskeleton. How the polarization is initiated, or how the different raft proteins are sorted from one another, is not yet known. At the front of the cell, activated chemokine receptors are the best candidates for initiating polarization.

Reference:

Gómez-Moutón, C., et al. 2001. Proc. Natl. Acad. Sci. USA. 98:9642–9647.[Abstract/Full Text]

William A. Wells

wellsw{at}rockefeller.edu

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This Article Full Text (PDF, 142K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wells, W. A. Search for Related Content PubMed Articles by Wells, W. A. Social Bookmarking                            What's this?