Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text (PDF, 499K) 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?

Lipid-driven sorting and fission

Ld (green) not Lo (red) lipids are preferentially pulled into tubes. GOUD/EMBO

Changes in membrane shape during trafficking require proteins, and those proteins are thought to operate mechanically to extrude or squeeze membranes. But biological membranes are also thought to be poised near a phase transition between liquid-ordered (L_o) and liquid-disordered (L_d) states. Aurélien Roux, Patricia Bassereau, Bruno Goud (Institut Curie, Paris, France), and colleagues now report that in vitro tube formation is favored from L_d domains, and phase separation induces fission. Proteins that affect lipid distributions in vivo may thus favor or disfavor tubulation and fission events during protein trafficking.

The preferential tubulation from L_d domains makes sense, as reduced interactions between lipid head groups make these domains more easily deformable. The French team used biotinylated lipids and kinesin-laden beads to pull tubes out of lipid vesicles in vitro. More tubes were pulled from L_d domains. But even in vesicles lacking visible segregation between L_d and L_o domains, the pulled tubes are enriched in lipids from the L_d phase because the other lipids sort out of the tubes.For some lipid compositions such a sorting event promotes phase separation in tubes. In vitro, the induction of phase separation (via photooxidation of cholesterol) induced fission; in many cases this clearly occurred at an L_o/L_d boundary. If this holds up in vivo, those interested in trafficking may have to think about lipid dynamics as much as protein mechanics. Membrane fission proteins have been thought of as motors driving a constriction event, but "the main function of these proteins," says Goud, "might be to help promote this phase transition."

Reference:

Roux, A., et al. 2005. EMBO J. doi:10.1038/sj.emboj.7600631.[CrossRef][Medline]

William A. Wells

wellsw{at}rockefeller.edu

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This Article Full Text (PDF, 499K) 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?