This enzyme is known to be bifunctional, as both mannose-6-phosphate isomerase (EC 5.3.1.8) (PMI) and mannose-1-phosphate guanylyltransferase (EC 2.7.7.22) in Pseudomonas aeruginosa, Xanthomonas campestris, and Gluconacetobacter xylinus. The literature on the enzyme from E. coli attributes mannose-6-phosphate isomerase activity to an adjacent gene, but the present sequence has not been shown to lack the activity. The PMI domain is C-terminal. [Cell envelope, Biosynthesis and degradation of surface polysaccharides and lipopolysaccharides]
Jiyao W et al.(2023). "The conserved domain database in 2023.",