The xcexb2-barrel is a ubiquitous fold that is deployed to accomplish a wide variety of biological functions including membrane-embedded pores. Key influences of xcexb2-barrel lumen diameter include the number of xcexb2-strands (n) and the degree of shear (S), the latter value measuring the extent to which the xcexb2-sheet is tilted within the xcexb2-barrel. Notably, it has previously been reported that the shear value for small antiparallel xcexb2-barrels (nxe2x89xa424) typically ranges between n and 2n. Conversely, it has been suggested that the xcexb2-strands in giant antiparallel xcexb2-barrels, such as those formed by pore forming cholesterol-dependent cytolysins (CDC), are parallel relative to the axis of the xcexb2-barrel, i.e. S=0. The S=0 arrangement, however, has never been observed in crystal structures of small xcexb2-barrels. Therefore, the structural basis for how CDCs form a xcexb2-barrel and span a membrane remains to be understood.