Actin paracrystalline sheets formed at the surface of positively charged liposomes.

Paracrystalline aggregates of F-actin spontaneously assemble at the surface of positively charged liposomes. This single-layered paracrystalline array is made up of parallel and juxtaposed actin filaments aligned in register and showing the typical 36-nm periodicity which corresponds to the half-pitch of the double helix strand. This crystallization of pure actin results from a direct interaction between actin and positively charged lipids and does not occur with negative or neutral lipids.