Substrate binding domain of an active sulfate transporter, a member of the type 2 periplasmic binding fold superfamily.
This family contains sulfate binding domain of CysP proteins that serve as initial receptors in the ABC transport of sulfate and thiosulfate in eubacteria. After binding the ligand, CysP interacts 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. The CysP proteins belong to the PBP2 superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.
Jiyao W et al.(2023). "The conserved domain database in 2023.",