  Monte Carlo simulations using an explicit solvent model indicate a new
pathway for translocation of a polymer chain through a lipid bilayer. We
consider a polymer chain composed of repeat units with a given hydrophobicity
and a coarse-grained model of a lipid bilayer in the self-organized liquid
state. By varying the degree of hydrophobicity the chain undergoes an
adsorption transition with respect to the lipid bilayer. Close to the
transition point, at a properly balanced hydrophobicity of the chain, the
membrane becomes transparent with respect to the chain. At the same time the
solvent permeability of the bilayer is strongly increased in the region close
to adsorbed chain. Our results indicate that the critical point of adsorption
of the polymer chain interacting with the fluctuating lipid bilayer could play
a key role for the translocation of molecules though biological membranes.
