The phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS), a major carbohydrate active transport system, catalyzes the phosphorylation of incoming sugar substrates concomitant with their translocation across the cell membrane. The enzyme II SorABFM PTS system is involved in L-sorbose transport. keto-L-sorbose(out) + N(pros)-phospho-L-histidyl-[protein] = L-histidyl-[protein] + L-sorbose 1-phosphate(in) Dimer of dimers. By L-sorbose. The PTS EIIB type-4 domain is phosphorylated by phospho-EIIA on a histidyl residue. Then, it transfers the phosphoryl group to the sugar substrate concomitantly with the sugar uptake processed by the PTS EIIC type-4 domain.