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The periplasmic-binding component of ABC transport system specific for sn-glycerol-3-phosphate; possesses type 2 periplasmic binding fold. This group includes the periplasmic component of an ABC transport system specific for sn-glycerol-3-phosphate (G3P) and closely related proteins from archaea and bacteria. Under phophate starvation conditions, Escherichia coli can utilize G3P as phosphate source when exclusively imported by an ATP-binding cassette (ABC) transporter composed of the periplasmic binding protein, UgpB, the transmembrane subunits, UgpA and UgpE, and a homodimer of the nucleotide binding subunit, UgpC. Members of this group belong to the type 2 periplasmic-binding fold superfamily. PBP2 proteins are comprised of two globular subdomains connected by a flexible hinge and bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap. The majority of PBP2 proteins function in the uptake of small soluble substrates in eubacteria and archaea. After binding their specific ligand with high affinity, they can interact with a cognate membrane transport complex comprised of two integral membrane domains and two cytoplasmically located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",