Fig. 4.

²²Na⁺ transport is a primary event. Membrane vesicles (protein concentration 3.2 mg/mL) in 50 mM Mops buffer (pH 6.0) containing 20 mM MgSO₄, 20 mM NaCl, 8 mM DTE, and 2.25 mg/L resazurin showed ²²Na⁺ transport upon addition of 7.5 μg ferredoxin, 5 mM titanium citrate, and 3.5 mM NAD⁺ (squares). ETH 2120 (100 μM) was added 6 min before (upward-pointing triangles) or 4 min after (downward-pointing triangles) addition of NAD⁺. SF 6847 (100 μM) (diamonds) was added 6 min before addition of NAD⁺. Arrow indicates addition of NAD⁺.