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© The Rockefeller University Press, 0021-9525/2002/9/829 $5.00
The Journal of Cell Biology, Volume 158, Number 5, September 2, 2002 829-829

A zipper designed to snag

SNARE proteins zipper up during fusion.

In the current model of vesicle membrane fusion, a helical bundle formed by v- and t-SNARE proteins works like a zipper, drawing closed first at the membrane-distal end, and zipping up toward the membrane-proximal end of the bundle. On page 929, Melia et al. describe the first functional test of this model. Besides confirming that zippering occurs in the membrane-distal to membrane-proximal direction, the results uncover a new regulatory step in vesicle fusion.

The authors examined fusion between liposomes reconstituted with mammalian SNARE proteins and added peptides that bound to either the membrane-proximal COOH terminus or membrane-distal NH₂ terminus of the t-SNARE. As predicted by the model, the NH₂- directed peptides block initial contact between v- and t-SNARES and inhibit fusion, but, once zippering has started, fusion is resistant to these NH₂-directed peptides. The COOH-directed peptides, however, dramatically increase the rate of fusion, a result not predicted by the model.

Melia et al. suggest that the COOH-directed peptides are affecting a previously unrecognized inherent regulatory switch in the t-SNARE, which they name the t_C fusion switch. In its default state, the switch is off and pauses zippering at about the midpoint of the bundle. The right peptide, such as the COOH-directed peptides or perhaps a sequence from a regulatory protein, can structure the coil, turn the switch on, and accelerate fusion.

Alan W. Dove

alanwdove{at}earthlink.net

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Related Article

Regulation of membrane fusion by the membrane-proximal coil of the t-SNARE during zippering of SNAREpins

Thomas J. Melia, Thomas Weber, James A. McNew, Lillian E. Fisher, Robert J. Johnston, Frank Parlati, Lara K. Mahal, Thomas H. Söllner, and James E. Rothman
J. Cell Biol. 2002 158: 929-940. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF, 498K) 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 Dove, A. W. Search for Related Content PubMed Articles by Dove, A. W. Related Collections Related Article Social Bookmarking                            What's this?