. 1996 Dec 10;93(25):14446–14451. doi: 10.1073/pnas.93.25.14446

Table 1.

Uptake of ²²Na⁺ and ⁸⁶Rb⁺ upon imposition of an inwardly directed pH gradient across TetA(L) proteoliposomes, and cross-inhibition by monovalent cations

Cation solute	Uptake,^* μmol/mg of protein at 1 min	% inhibition by
Cation solute	Uptake,^* μmol/mg of protein at 1 min	Na⁺	Li⁺	K⁺
²²Na⁺	20.5	—	73	83
⁸⁶Rb⁺	18.4	93	ND	—

ND, Not determined.

TetA(L) proteoliposomes were prepared and loaded with NH₄Cl as described in Materials and Methods. Uptake was initiated by dilution into ammonium-free buffer containing either 1 mM ²²Na⁺ or 1 mM ⁸⁶Rb⁺ (K⁺) plus no added cations, 10 mM LiCl, 100 mM KCl, or 100 mM NaCl, as indicated. Samples were filtered at intervals. The amount of uptake of the radiolabeled cation in the absence of inhibitors was calculated from the 1-min point.