Our comparative genomics suggests this protein family to be a subunit of a selenium-dependent molybdenum hydroxylase, although the substrate is not specified. This protein is suggested by Bebien, et al., to be the molybdenum-binding subunit of a molydbopterin-containing selenate reductase. Xi, et al, however, show that mutation of this gene in E. coli conferred sensitivity to adenine, suggesting a defect in purine interconversion. This finding, plus homology of nearby genes in a 23-gene purine catabolism region in E. coli to xanthine dehydrogase subunits suggests xanthine dehydrogenase activity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",