Viral fusion: how Flu induces dimples on liposomes.

Membrane fusion--a basic cellular process enabling crucial cellular functions such as membrane trafficking--is mechanistically only partially understood. Most of the existing knowledge has come from studying host-cell entry of viruses with lipid bilayer envelopes, which proceeds through fusion of viral and host-cell membranes.Crystal structures for a number of viral fusion proteins facilitating this process have contributed substantially to our understanding. One of the next challenges is to merge these high-resolution structures of soluble parts of fusion effectors with native structural information on the proteins in the course of their functional interactions with the target membranes. In this issue of The EMBO Journal,Lee (2010) presents an elegant example of such a study,probing the early interaction of the influenza virus with liposomes by cryo-electron tomography (cryoET).