FIG. 6.

atp2-227 atp3Δ ρ° yeast generates a greater inner mitochondrial membrane potential in response to ATP compared to atp3Δ ρ° yeast. At the indicated times, 250 μg of mitochondria isolated from the indicated strains (M), ATP to a final concentration of 1 mM (A), and 50 ng of valinomycin in 95% ethanol (V) were added to a final volume of 2.5 ml of reaction buffer containing 1 μM rhodamine 123 (Molecular Probes) (11, 14). The relative fluorescence was monitored using a FluoroMax-2 spectrofluorometer operating in the steady-state mode. The samples were excited at 502 nm, and emission was measured at 525 nm. Strains: wild type (WT) ρ⁺, PTY44 ρ⁺; WT ρ°, PTY44 ρ°; atp3Δ ρ°, JTY3; atp2-227 atp3Δ ρ°, JTY6; atp2Δ atp3Δ ρ⁺, TCY60; atp2-227 ρ⁺, TCY55.