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. This system is involved in alpha- and beta-glucoside transport (By similarity). The EIIC domain forms the PTS system translocation channel and contains the specific substrate-binding site. The EIIB domain is phosphorylated by phospho-EIIA on a cysteinyl or histidyl residue, depending on the transported sugar. Then, it transfers the phosphoryl group to the sugar substrate concomitantly with the sugar uptake processed by the EIIC domain. The EIIA domain is phosphorylated by phospho-HPr on a histidyl residue. Then, it transfers the phosphoryl group to the EIIB domain.