| description | Protein with at least one transmembrane beta stranded domain, a membrane-spanning stretch, typically 5-10 amino acids long, whose peptide backbones are almost fully extended with the sidechains of two neighboring residues projected in the opposite direction from the backbone. Two or more hydrogen bonded (parallel or anti-parallel) beta strands form a beta sheet. A beta barrel is formed by a closed beta sheet around a central pore. Beta barrels consist usually of an even number of beta strands (between 8 and 24), they are found only in bacterial outer membranes, mitochondria and plastids |
