Reconstitution of Semliki forest virus membrane.

The spike glycoproteins of the Semliki forest virus membrane have been incorporated into vesicular phospholipid bilayers by a detergent-dialysis method. The detergent used was beta-D-octylglucoside which is nonionic and has an exceptionally high critical micellar concentration which facilitates rapid removal by dialysis. The vesicles obtained were of varying sizes and had spikes on their surface. Two classes of vesicles were preferentially formed, small protein-rich and large lipid-rich (average lipid to protein weight ratios, 0.22 and 3.5, respectively). Both classes of vesicles retained the hemagglutinating activity of the virus. The proteins were attached to the lipid bilayer by hydrophobic peptide segments, as in the viral membrane. Most of the proteins were accessible to proteolytic digestion from the outside, suggesting an asymmetric orientation.