A strong promoter (Ncpp) enhances expression of TRK1 protein but depresses expression of HAK1 protein. (A) Western blot analysis of HA-tagged Trk1p produced via the native NcTRK1 promoter (▲, strain {TRK1-HA}) or via the NcPMA1 promoter (Ncpp; strain {NcppTRK1-HA}; ). Steady-state enhancement by Ncpp was ∼5-fold at low [K+]o and ∼10-fold at high [K+]o. For the inset, the load is 20 μg membrane protein in each lane. (B) Western blot analysis of HA-tagged Hak1p produced via the native NcHAK1 promoter (strain {HA-HAK}; ■) or via the NcPMA1 promoter (Ncpp; strain {NcppHA-HAK1}; ). Quantitative gels from two separate experiments were scaled (to values at [K+]o of 1 mM) and averaged. Note that steady-state depression by Ncpp, about 2.5-fold at low [K+]o, was released at high [K+]o. Methods were the same as those described for Fig. 1, 4, and 5. For the inset, the load is 1.5 μg for each lane.