Maltose-binding protein (MBP) is a part of the maltose/maltodextrin system of Escherichia coli, which is responsible for the uptake and efficient catabolism of maltodextrins.

Crystal structures have shown that MBP is divided into two distinct globular domains that are connected by three short polypeptide segments.

Comparison of the structures of the liganded and unliganded forms of MBP has shown that the binding of maltose induces a major conformational change that closes the groove by a rigid motion of the two domains around the linking polypeptide hinge.

[6][7] The equilibrium unfolding of MBP can be modelled by a two-state mechanism with a stability ∆G(H2O) equal to 9.45 kcal mol−1 at 25 °C, pH 7.6.

All the gene involved in the transport of maltose/maltodextrin, including malE, are clustered in the malB region of E. coli and organized in two divergent operons: malE-malF-malG and malK-lamB.

A first study of the relations between structure and functions of MBP was performed by random insertion of a short DNA fragment, coding for a BamHI restriction site, into the malE gene.

[21][22] The permissive sites that were internal to MBP, were used to insert antigenic peptides and challenge the immune response in mice.

[26] When the recombinant MBP includes a signal peptide, the fusion protein can be exported into the periplasmic space, which facilitates its purification since the periplasmic fluid contains only a limited number of proteins and can be recovered either by an osmotic shock or by permeabilization of the bacterial outer membrane with antibiotics such as Polymyxin B.

[24][29] When the recombinant MBP includes either a defective or no signal peptide the fusion protein remains within the bacterial cytoplasm from where it can be recovered by breaking open the cells.