Channels in planar bilayers made from commercially available lipids.

Planar bilayer membranes were made from commercially available lipids. With various lipids, originating from biological sources, such as egg yolk phosphatidylcholine, soybean phosphatidylcholine or bovine brain phosphatidylserine, spontaneously fluctuating channels could be observed. Spontaneous channel activity could not be observed in planar bilayers made from synthetic lipids, such as 1,2 diphytanoyl 3-sn-phosphatidylcholine. It is concluded that the observed channels are due to proteolipids, being present as impurities in the lipid material.