Protein complex facilitating ATP-dependent maltose transport through inner cell membrane (periplasm to cytoplasm) in Gram-negative bacteria. In E. coli the system is composed of a periplasmic maltose-binding protein (MBP), two integral membrane proteins, MalF and MalG, and two copies of the cytoplasmic ATP-binding cassette MalK. [ http://www.ncbi.nlm.nih.gov/pubmed/18033289 ]