Glucose permease IIA domain functions as part of phosphorylation of sugars, a phosphoryl group is transferred from Hpr to IIA Domain via a histidyl residue then to IIB domain- then finally to a sugar which is being transported into the organism. It is part of the bacterial phosphotransferase system (PTS) phosphorylation cascade. It should be noted that there is very little sequence similarity across the enzymes containing IIA that are specific to different sugars they inevitably transport.