Properties of a Viral Fusion Protein

  • Robert W. Doms
  • Ari Helenius


The mechanisms by which proteins mediate biological membrane fusion are not clearly understood. We have analyzed acid-induced changes in influenza hemagglutinin (HA), a viral membrane fusion factor, and correlated them with its acid-triggered fusion activity. Our results, some of which are reported here for the first time, indicate that the extramembraneous domain of HA acquires amphiphilic properties when converted to the fusion active form by mild low pH treatment. We show that each HA subunit acquires the ability to bind approximately 10 additional molecules of Triton X-100. A fusion inactive precursor of HA, termed HAO, does not acquire this property. The trimeric ectodomain fragment of HA tends, moreover, to dissociate after acid treatment into dimers and trimers. A model for the acid-induced changes in HA and the mechanism of fusion are discussed.


Influenza Virus Membrane Fusion Hydrophobic Moiety Semliki Forest Virus Fusion Activity 
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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Robert W. Doms
    • 1
  • Ari Helenius
    • 1
  1. 1.Department of Cell BiologyYale University School of MedicineNew HavenUSA

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