L. Chernomordik et al., THE HEMIFUSION INTERMEDIATE AND ITS CONVERSION TO COMPLETE FUSION - REGULATION BY MEMBRANE-COMPOSITION, Biophysical journal, 69(3), 1995, pp. 922-929
To fuse, membranes must bend. The energy of each lipid monolayer with
respect to bending is minimized at the spontaneous curvature of the mo
nolayer. Two lipids known to promote opposite spontaneous curvatures,
lysophosphatidylcholine and arachidonic acid, were added to different
sides of planar phospholipid membranes. Lysophosphatidylcholine added
to the contacting monolayers of fusing membranes inhibited the hemifus
ion we observed between lipid vesicles and planar membranes. In contra
st, fusion pore formation depended upon the distal monolayer of the pl
anar membrane; lysophosphatidylcholine promoted and arachidonic acid i
nhibited. Thus, the intermediates of hemifusion and fusion pores in ph
ospholipid membranes involve different membrane monolayers and may hav
e opposite net curvatures. Biological fusion may proceed through simil
ar intermediates.