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 SorABCD PTS system is involved in L-sorbose transport. Induced by L-sorbose and repressed by D-glucose. The EIIA type-4 domain is phosphorylated by phospho-HPr on a histidyl residue. Then, it transfers the phosphoryl group to the EIIB type-4 domain.