D-galactose-binding periplasmic protein (GGBP)

D-galactose-binding periplasmic protein (GGBP) is a soluble periplasmic protein in *Escherichia coli* encoded by the **mglB** gene. It is essential for the high-affinity uptake of D-galactose and D-glucose, acting as the primary sugar-binding component for the MglABC ATP-binding cassette (ABC) transporter system. Structurally, GGBP is a monomeric protein of ~32–36 kDa, composed of two globular α/β domains connected by a flexible hinge region; the sugar-binding site is deeply buried in the cleft between the domains[3][4][1][8]. In addition to transport, GGBP is crucial for chemotaxis toward galactose and glucose, serving as the initial recognition element for the Trg chemoreceptor, thereby transducing external sugar concentrations into intracellular signaling for directed movement[4][5][6]. While not a direct therapeutic target, it is extensively used in the engineering of biosensors, especially for glucose, due to its conformational changes upon ligand binding[3]. GGBP’s physiological and chemotactic roles make it essential for E. coli’s nutrient acquisition and environmental adaptation.

Other names

D-galactose/D-glucose-binding proteinGlucose/galactose-binding proteinMglB (gene name)GBPGGBP

Not applicable (no therapeutic drugs interact directly for clinical use)