The versatile beta-barrel membrane protein.

The beta-barrel membrane protein is found in the outer membranes of bacteria, mitochondria and chloroplasts. Approximately 2-3% of the genes in Gram-negative bacterial genomes encode beta-barrels. Whereas there are fewer than 20 known three-dimensional beta-barrel structures, genomic databases currently contain thousands of beta-barrels belonging to dozens of families. New research is revealing the variety of beta-barrel structures and the variety of functions performed by these versatile proteins.