 The former can transport aromatic β-glucosides and cellobiose, as well as Chb.However, only Chb induces expression of the "chb" operon.While the Lac porters consist of two polypeptide chains (IIA and IICB), the Chb porters of "E. coli" and "B. burgdorferi" consist of three (IIA, IIB and IIC).