Developmental fusion proteins

3D reconstruction of EFF-1 in a membrane with a protomer crystal structure fitted (1)

The first family of bona fide extracellular cell–cell fusion proteins to be identified was in C. elegans. The founding members of this cell–cell fusion family (FF) are the epithelial fusion failure 1 (EFF-1) and the anchor-cell fusion failure 1 (AFF-1) proteins. Both proteins have been shown to be sufficient to fuse cells in vivo, and induce fusion of insect and mammalian cells in cell culture when expressed ectopically. FF-mediated fusion is bilateral and homotypic, that is, dependent on the presence of FF proteins on both fusing membranes, unlike viral fusion proteins. 

We study the structure of EFF-1 and AFF-1 on genuine membranes by using cryo electron tomography and sub-volume averaging. 

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Further reading 

1. Zeev-Ben-Mordehai T, Vasishtan D, Siebert CA, Whittle C, & Grünewald K (2014) Extracellular Vesicles: A Platform for the Structure Determination of Membrane Proteins by Cryo-EM. Structure 22(11):1687-1692. external link

2. Zeev-Ben-Mordehai T, Vasishtan D, Siebert CA, & Grünewald K (2014) The full-length cell-cell fusogen EFF-1 is monomeric and upright on the membrane. Nat Commun 5:3912.