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Figure 7.
Figure 7 High membrane curvature promotes membrane fusion. (A)
Example of endophilin N-BAR tubules made from liposomes extruded
to a size cutoff of 400 nm. (B) Emission spectra from mixed
liposomes in the absence and presence of calcium (which promotes
fusion) and Triton (to obtain total donor fluorescence). See
Materials and methods for details of the assay. (C) FRET assay
of membrane fusion, showing dilution of the FRET pair into
unlabelled liposome in the presence of the N-BAR (see Results).
The N-BAR control has no unlabelled liposomes and thus there can
be no dilution of the FRET pair. The BAR domain does not lead to
membrane fusion. As highly curved membranes are more fusogenic,
we believe that the fusion seen with the N-BAR domain is a
readout of the efficiency of curvature generation. (D)
Comparison of mutants and WT N-BAR domains at 55  M
in the fusion assay. Values displayed in the bar chart  s.e.m.
are the difference in the ratios of emission maxima between
experiment (mixed liposomes (530/585 nm)) and controls
(uniformly labelled liposomes (530/585 nm)) (see Results).
Studentʼs t-test ^*P<0.001, ^**P<0.2.
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