Transmembrane passage of hydrophobic compounds through a protein channel wall

In this paper Hearn et al. present the structure of an Escherichia coli long-chain fatty acid importer, FadL, which reveals an opening in the wall of its transmembrane beta-barrel. They further show that a mutant in which this opening is constricted is unable to transport substrate, and conclude that importers, like exporters, may exploit lateral diffusion for the transport of hydrophobic substrates.