The function of this family is unknown, but it is upregulated in response to salt stress in Populus balsamifera. It is also found at the C-terminus of an fructose 1,6-bisphosphate aldolase from Hydrogenophilus thermoluteolus. Arthrobacter nicotinovorans ORF106 is found in the pA01 plasmid, which encodes genes for molybdopterin uptake and degradation of plant alkaloid nicotine. The structure of one has been solved and the domain forms an a/b barrel dimer. Although there is a clear duplication within the domain it is not obviously detectable in the sequence.