After the virus binds to the target cell surface and is endocytosed, the low pH of the endosome causes the viral HA (hemagglutinin) to undergo a structural change which frees the fusion peptide of its HA2 subunit allowing it to interact with the endosome membrane. The transmembrane domain of the HA2 (inserted into the viral membrane) and the fusion peptide (inserted into the endosomal membrane) are in juxtaposition in the acidic pH structure of HA. The concerted structural change of several hemagglutinin molecules then opens a pore through which the viral RNP will be able to pass into the host cell cytosol.
Marsh, M, Helenius, A
Whittaker, GR, Sieczkarski, SB
Wilschut, J, Scholma, J, Stegmann, T, Morselt, HW
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