This family consists of several hypothetical bacterial proteins of around 250 residues in length. The function of this family is unknown. The structure of this cytoplasmic domain was solved by the Midwest Center for Structural Genomics (MCSG). The structure has been classified as part of the Class-I Glutamine amidotransferase superfamily owing to similarity with other known structures. The monomer combines with itself to form a hexamer, and this hexamer exposes a potential catalytic surface rich in Glu, Asp, Tyr, Ser.Trp and His residues [1].

1: Novel hexamerization motif is discovered in a conserved cytoplasmic protein from Salmonella typhimurium. Petrova T, Cuff ME, Wu R, Kim Y, Holzle D, Joachimiak A; J Struct Funct Genomics. 2007;8:19-25. PMID:17968677