The phosphoenolpyruvate-dependent sugar phosphotransferase system (sugar PTS), a major carbohydrate active transport system, catalyzes the phosphorylation of incoming sugar substrates concomitantly with their translocation across the cell membrane. The enzyme II CmtAB PTS system is involved in D-mannitol transport. Homodimer or homotrimer. Seems to be a monomer when not phosphorylated. The PTS EIIA type-2 domain is phosphorylated by phospho-HPr on a histidyl residue. Then, it transfers the phosphoryl group to the PTS EIIB type-2 domain.