Study of F-actin interaction with planar and liposomal bilayer phospholipid membranes.

Interaction of the cytoskeletal protein F-actin with planar bilayer lipid membrane (BLM) induced formation of single ionic channels in both NaCl and KCl bathing solutions. We also recorded noiselike high-currentjumps with a mean conductivity of approximately 160 pS, which might represent the simultaneous opening and closing of several channels of lower conductivity. The ratio of cation to anion permeabilities (Pc/Pa) of the BLM with many channels in KCl was 26 +/- 2. Freeze-fracture electron microscopy revealed fibrillar-like structures on the hydrophobic surfaces of liposomal membranes. We also observed some structural features giving evidence for the penetration of F-actin fibers through an artificial phospholipid membrane. We suggest that the F-actin/lipids complexes can transmit electric signals in synaptic and other intercellular contacts.