前期研究暗示SdpsT是一个可能具有钠（锂）/氢逆向转运蛋白功能的新型PiT家族转运蛋白，但其确切功能仍然未定。因此，本项目拟采用基于RSO膜微囊的同位素32P或35S标记的检测技术，鉴定SdpsT具体作为何种PiT家族转运蛋白行使功能；采用基于反转膜微囊的吖啶橙荧光猝灭恢复法或同位素22Na的检测技术，鉴定SdpsT具体是通过行驶钠（锂）/氢逆向转运蛋白功能输出Na+，还是通过偶联PiT家族转运蛋白功能输出Na+。作为新型PiT家族转运蛋白，SdpsT的功能鉴定，不仅可以揭示该蛋白转运无机磷酸/无机硫酸以及耐盐碱的分子机制，而且可以增进人们对PiT家族转运蛋白和钠（锂）/氢逆向转运蛋白在细菌耐盐碱方面的认识。

Preliminary experiments suggest that SdpsT may be a novel PiT family transporter with Na+(Li+)/H+ antiport activity, but its function hasn’t been identified experimentally as yet. In this project, we plan to identify the exact function of SdpsT as a novel PiT family transporter by analyzing the uptake of 32P labeled inorganic phosphate or 35S labeled inorganic sulfate based on RSO membrane vesicles containing pUC-sdpsT. Also, we plan to identify whether SdpsT extrudes Na+ indenpendtly as a Na+(Li+)/H+ antiporter or SdpsT extrudes Na+ as a PiT family transporter by being coupled to the transportation of inorganic phosphate or inorganic sulfate through the acridine orange fluorescence dequenching method based on inverted membrane vesicles or by analyzing the uptake of 22Na+ by inverted membrane vesicles containing pUC-sdpsT. As a novel PiT family transporter, identification of SdpsT will be very helpful to not only understand molecular mechanism of inorganic phosphate or inorganic sulfate transportation by SdpsT and halo-alkali tolerant molecular mechanism of SdpsT, but also enhance our knowledge of the key role of PiT family transporters and Na+(Li+)/H+ antiporters in bacterial halo-alkali tolerance.