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Substrate-binding domain of uncharacterized protein Yhfz from Shigella Flexneri; the type 2 periplasmic-binding protein fold This subfamily contains periplasmic binding protein type II (BPBII). This domain is found in solute binding proteins that serve as initial receptors in the ABC transport, signal transduction and channel gating. The PBPII proteins share the same architecture as periplasmic binding proteins type I (PBPI), but have a different topology. They are typically 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 PBPII 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. Besides transport proteins, the family includes ionotropic glutamate receptors and unorthodox sensor proteins involved in signal transduction. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",