According to the literature, structural domains which comprise this superfamily correspond to the structure of one of the two 6-stranded beta barrels which comprise MreC, a rod shape-determining protein in E.coli. More generally it is involved in cell shape determination of bacteria even when they are not rod shaped.

Pfam annotates this as a single chain domain but the structure of this superfamilies's representative domain corresponds to just one of the two beta barrels that comprise the whole chain. Thus, for specificity, the term domain 2 has been included in the name.