In molecular biology, phosphotransferases are proteins in the transferase family of enzymes (EC number 2.7) that catalyze certain chemical reactions.
The general form of the phosphorylation reactions they catalyze is:
The PTS transports sugars (such as glucose, mannose, and mannitol) into the cell.
The first step of this reaction is phosphorylation of the substrate via phosphotransferase during transport.
Due to the negative charge of the phosphate, this Glc-6P can no longer freely leave the cell.