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. Author manuscript; available in PMC: 2015 Apr 1.
Published in final edited form as: Curr Opin Microbiol. 2014 Feb 8;0:8–15. doi: 10.1016/j.mib.2014.01.002

Fig. 4. The uptake hexose phosphate (UHP) transport system.

Fig. 4

The Uhp system consists of four proteins: UhpA, B, C, and T. UhpC and UhpT are homologous members of the major facilitator superfamily, serving the function of receptor/transporter and transporter, respectively. UhpB and A are the sensor kinase and response regulator of the regulatory two component system, serving to convey the signal of glucose-6-phosphate (G6P) availability to upregulate the expression of the uhpT gene. The 2 TMS membrane domain of the UhpB protein senses when the substrate, G6P, for which UhpC is highly specific, is bound to its external surface. Then with G6P bound to UhpC, and with UhpC in direct contact with UhpB, UhpB utilizes ATP to autophosphorylate its central domain. Once UhpB is phosphorylated, UhpB can donate its phosphoryl group to UhpA, which binds to multiple sites between -80 and -32 upstream of the start site of the uhpT gene, functioning as an enhancer in the promoter region. →, transcriptional activation.