Mechanism of Membrane Fusion Mediated with Viral Proteins
The study of membrane fusion is an important subject of cell biology, especially intracellular transport system, which works through membrane fusion of transport vesicles. Nevertheless we have few informations about cellular proteins responsible for fusion reaction. Study of fusion mechanism has been done mainly with viral fusion-active proteins. The most intensively studied fusion-active protein is hemagglutinin (HA) of influenza A virus, and it has been shown that fusion-active subunit of HA is transformed into a long α-helical coiled coil at low pH and bridges two adjacent membranes with two hydrophobic regions, namely the fusion peptide region and the anchor region. Flexible bridge of the coiled coil may mediate mixing of the lipid bilayers, eventually resulting in membrane fusion. In this review, we focus on the molecular mechanism of membrane fusion, which has been elucidated mainly through the studies with influenza HA protein.