Part of the ABC transporter complex GgtABCD involved in the uptake of the osmoprotective compounds glucosylglycerol (GG), sucrose and trehalose (PubMed:11081796). Responsible for the translocation of the substrate across the membrane (Probable). The complex is composed of two ATP-binding proteins (GgtA), two transmembrane proteins (GgtC and GgtD) and a solute-binding protein (GgtB). Expression is very low in cells grown in basal medium but increases significantly after a salt shock. Inactivation of the gene results in loss of the ability to take up glucosylglycerol and sucrose, as well as to accumulate exogenous trehalose. Insertion causes leakage of glucosylglycerol from the cells into the medium. Belongs to the binding-protein-dependent transport system permease family.