Two-phase partitioning applied to changes in phospholipid asymmetry.

In summary aqueous two-phase polymer partition is a useful addition to the range of techniques available for determining lipid asymmetry in model and in biological membrane systems. The methodology is straightforward, the experimental requirements simple and the materials used inexpensive. We have demonstrated its usefulness in several model membrane systems rendered asymmetric by the establishment of a membrane potential across the lipid bilayer and in monitoring Ca(2+)-induced asymmetry in human erythrocytes.