Outer membrane of Salmonella. Isolation of protein complex that produces transmembrane channels

Salmonella typhimurium outer membrane protein complexes can be reconstituted with lipopolysaccharide and phospholipids into membrane vesicles. These vesicles are permeable to a variety of low molecular weight compounds, but not to oligo- and polysaccharides of molecular weight higher than 700. A protein complex participating in selective membrane permeability can be isolated by gel filtration in the presence of sodium dodecyl sulfate. The active fractions contain three major protein species. The Braun lipoprotein is not associated with this subset of outer membrane proteins.