This family consist of trehalose-phosphatases EC:3.1.3.12 these enzyme catalyse the de-phosphorylation of trehalose-6-phosphate to trehalose and orthophosphate. The aligned region is present in trehalose-phosphatases and comprises the entire length of the protein it is also found in the C-terminus of trehalose-6-phosphate synthase EC:2.4.1.15 adjacent to the trehalose-6-phosphate synthase domain - Pfam:PF00982. It would appear that the two equivalent genes in the E. coli otsBA operon [2] otsA the trehalose-6-phosphate synthase and otsB trehalose-phosphatase (this family) have undergone gene fusion in most eukaryotes e.g. Swiss:P31688 and Swiss:P93653. Trehalose is a common disaccharide of bacteria, fungi and invertebrates that appears to play a major role in desiccation tolerance [1].

1: Trehalose-6-phosphate phosphatases from Arabidopsis thaliana: identification by functional complementation of the yeast tps2 mutant. Vogel G, Aeschbacher RA, Muller J, Boller T, Wiemken A; Plant J 1998;13:673-683. PMID:9681009

2: Analysis of the otsBA operon for osmoregulatory trehalose synthesis in Escherichia coli and homology of the OtsA and OtsB proteins to the yeast trehalose-6-phosphate synthase/phosphatase complex. Kaasen I, McDougall J, Strom AR; Gene 1994;145:9-15. PMID:8045430