M6P can be converted to F6P by mannose-6-phosphate isomerase and subsequently utilized in several metabolic pathways including glycolysis and capsular polysaccharide biosynthesis.

[3] MPI must convert an aldose (mannose) to a ketose (fructose), in addition to opening and closing the rings for these sugars.

[9] MPI is composed of 440 amino acid residues, with one active site and one zinc ion (Zn2+) ligand.

This increased space created by the threonine allows the rotation of the C2-C3 bond, which enables the necessary cis-enediol intermediate to be formed.

Additionally M6P is an important signaling molecule, especially for transport to lysosomes: disorders affecting MPI activity may affect cellular ability to quickly produce M6P from plentiful F6P, and therefore vesicle traffic to lysosomes and endosomes may be altered, potentially negatively impacting the cell.