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Publication Abstract from PubMed

Cell-cell fusion proteins are essential in development. Here we show that the C. elegans cell-cell fusion protein EFF-1 is structurally homologous to viral class II fusion proteins. The 2.6 A crystal structure of the EFF-1 trimer displays the same 3D fold and quaternary conformation of postfusion class II viral fusion proteins, although it lacks a nonpolar "fusion loop," indicating that it does not insert into the target membrane. EFF-1 was previously shown to be required in both cells for fusion, and we show that blocking EFF-1 trimerization blocks the fusion reaction. Together, these data suggest that whereas membrane fusion driven by viral proteins entails leveraging of a nonpolar loop, EFF-1-driven fusion of cells entails trans-trimerization such that transmembrane segments anchored in the two opposing membranes are brought into contact at the tip of the EFF-1 trimer to then, analogous to SNARE-mediated vesicle fusion, zip the two membranes into one.

Structural basis of eukaryotic cell-cell fusion.,Perez-Vargas J, Krey T, Valansi C, Avinoam O, Haouz A, Jamin M, Raveh-Barak H, Podbilewicz B, Rey FA Cell. 2014 Apr 10;157(2):407-19. doi: 10.1016/j.cell.2014.02.020. PMID:24725407^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.