noun, plural: beta barrels
A large β-sheet that twists and coils to form a closed structure where the first strand is hydrogen bonded to the last.
Beta-strands in beta-barrels are typically arranged in an antiparallel fashion. These structures are commonly found in porins and other proteins that span cell membranes and in proteins that bind hydrophobic ligands in the barrel center, as in lipocalins.
Related forms: β-barrel.
Compare: alpha helix.
See also: transmembrane protein.