Blumwald E, Poole R J
Center for Plant Molecular Biology, McGill University, Montreal, Quebec, Canada H3A 1B1.
Plant Physiol. 1987 Apr;83(4):884-7. doi: 10.1104/pp.83.4.884.
Cell suspension cultures of sugar beet were grown at various salinities (0-200 millimolar NaCl). Their tolerance to Na(+) was comparable to that of the intact plant. Tonoplast vesicles were prepared by sucrose density gradient centrifugation of microsomal membranes and shown to be highly purified. The vesicles were subjected to a pH jump in the presence of acridine orange and the rate of recovery of fluorescence after addition of Na(+) was used as a measure of Na(+)-dependent H(+) efflux. In the presence of K(+) and valinomycin, the Na(+)/H(+) antiport showed saturation kinetics. Increasing Na(+) in the growth medium did not change the apparent K(m) for Na(+), but increased V(max) to about twice the control value, suggesting a specific induction of antiport synthesis by salt.
甜菜细胞悬浮培养物在不同盐度（0 - 200毫摩尔氯化钠）下生长。它们对Na(+)的耐受性与完整植株相当。通过蔗糖密度梯度离心微粒体膜制备液泡膜囊泡，并证明其高度纯化。在吖啶橙存在的情况下，对囊泡进行pH跃升，并将添加Na(+)后荧光恢复的速率用作Na(+)依赖性H(+)外流的指标。在K(+)和缬氨霉素存在的情况下，Na(+)/H(+)反向转运蛋白呈现饱和动力学。生长培养基中Na(+)的增加不会改变Na(+)的表观米氏常数(Km)，但会使最大反应速度(Vmax)增加到对照值的两倍左右，这表明盐对反向转运蛋白的合成有特异性诱导作用。
