(A) Cell water:medium distribution ratio of ³⁶Cl⁻ in various deletant strains. Cells were grown overnight in LCAPG and then incubated 2 h at 30°C in fresh medium plus 8 μM Na³⁶Cl. Cellular ³⁶Cl⁻ contents at the end of the incubation were determined as described in Materials and methods. Media were buffered with 5 mM K-citrate (initial pH 4.5, final pH 4.1; black bars), or 5 mM K-citrate, 10 mM bistris, 20 mM tris (initial pH 7.6, final pH 6.7; gray bars). Strains with deletions of the indicated genes were all in the background of BY4741. Bars labeled yhl, ybr, and ypr refer respectively to strains deleted in YHL008c, YBR235w, and YPR003c. Data represent single determinations except for bars labeled to indicate the number of determinations. Error bars are SEM. (B) Cellular Cl⁻ contents in low Cl⁻ media in paired experiments with control strain sul1. Cells were incubated in LCAPG media containing 8 μM ³⁶Cl⁻, and cellular Cl contents were determined after sufficient time to reach a steady-state distribution (>1.5 h). Bars represent mean ± SEM of the ratio between cellular [Cl⁻] in the test strain (nhx1, gef1, or vma1) and control strain sul1 at either pH 4.0 (black bars) or pH 7.0 (gray bars). Results of paired Student t tests (pH 4 and pH 7.0 combined): sul1 vs. nhx1, P < 0.02 (n = 4); sul1 vs. gef1, P < 10⁻⁵, n = 12; sul1 vs. vma1, P < 0.002, n = 6. (C) Cells:medium ³⁶Cl⁻ distribution ratio for sul1 and vma1 cells incubated as in A and B but with 0.2 mM DNP or DNP and 20 mM 2-deoxyglucose replacing 2% glucose during the 2 h incubation with ³⁶Cl⁻. The gray horizontal lines indicate a cells:medium ratio of unity.