Membrane sensor protein UhpC of the Major Facilitator Superfamily of transporters
Membrane sensor protein UhpC acts as both a sensor and a transport protein. It is part of the UhpABC signaling cascade that controls the expression of the hexose phosphate transporter UhpT. UhpC recognizes external glucose-6-phosphate (Glc6P) and induces transport by UhpT. It can also transport and sense Glc6P, and interacts with the histidine kinase UhpB, leading to the stimulation of the autokinase activity of UhpB. This group also includes the hexose phosphate transport protein UhpT from Chlamydia pneumoniae; it is a transport protein for sugar phosphate uptake. It is part of the Organophosphate:Pi antiporter (OPA) family of integral membrane proteins responsible for the transport of specific organophosphates or sugar phosphates across biological membranes with the simultaneous translocation of inorganic phosphate into the opposite direction. The UhpC group belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",