Cholesterol promotes hemifusion and pore widening in membrane fusion induced by influenza hemagglutinin

Subrata Biswas, Shu Rong Yin, Paul S. Blank, Joshua Zimmerberg

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Cholesterol-specific interactions that affect membrane fusion were tested for using insect cells; cells that have naturally low cholesterol levels (<4 mol %). Sf9 cells were engineered (HAS cells) to express the hemagglutinin (HA) of the influenza virus X-31 strain. Enrichment of HAS cells with cholesterol reduced the delay between triggering and lipid dye transfer between HAS cells and human red blood cells (RBC), indicating that cholesterol facilitates membrane lipid mixing prior to fusion pore opening. Increased cholesterol also increased aqueous content transfer between HAS cells and RBC over a broad range of HA expression levels, suggesting that cholesterol also favors fusion pore expansion. This interpretation was tested using both trans-cell dye diffusion and fusion pore conductivity measurements in cholesterol-enriched cells. The results of this study support the hypothesis that host cell cholesterol acts at two stages in membrane fusion: (1) early, prior to fusion pore opening, and (2) late, during fusion pore expansion.

Original languageEnglish (US)
Pages (from-to)503-513
Number of pages11
JournalJournal of General Physiology
Issue number5
StatePublished - May 2008
Externally publishedYes

ASJC Scopus subject areas

  • Physiology


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