Part of the ABC transporter complex NgcEFG-MsiK involved in N,N'-diacetylchitobiose ((GlcNAc)2) uptake. Responsible for the translocation of the substrate across the membrane. The complex is composed of two ATP-binding proteins (MsiK), two transmembrane proteins (NgcF and NgcG) and a solute-binding protein (NgcE). Constitutively expressed. Slightly induced by GlcNAc, (GlcNAc)2 and chitin. Repressed by DasR. Belongs to the binding-protein-dependent transport system permease family.