Kippen I, Hirayama B, Klinenberg J R, Wright E M
Proc Natl Acad Sci U S A. 1979 Jul;76(7):3397-400. doi: 10.1073/pnas.76.7.3397.
The uptake of citrate and alpha-ketoglutarate by membrane vesicles from rabbit renal brush border was studied by a rapid filtration technique. Both compounds exhibited transport characteristics similar to those seen for the sodium-dependent cotransport systems previously described for sugars and amino acids in brush border membranes. The estimated sodium-dependent Vmax and Km were 17 nmol per mg of protein per min and 0.18 mM for citrate and 17 nmol per mg of protein per min and 1.0 mM for alpha-ketoglutarate. The initial rate of citrate transport was 5 times that of sugars and amino acids under comparable conditions. Uptake rates of 0.1 mM citrate and alpha-ketoglutarate were inhibited by greater than 90% by 10 mM succinate, malate, fumarate, or oxaloacetate, indicating the presence in the brush border membrane of a transport system highly specialized for the renal conservation of intermediates of the tricarboxylic acid cycle.
采用快速过滤技术研究了兔肾刷状缘膜囊泡对柠檬酸盐和α-酮戊二酸的摄取。这两种化合物的转运特性与先前在刷状缘膜中描述的糖和氨基酸的钠依赖性共转运系统相似。估计柠檬酸盐的钠依赖性最大转运速率（Vmax）和米氏常数（Km）分别为每毫克蛋白质每分钟17纳摩尔和0.18毫摩尔，α-酮戊二酸的分别为每毫克蛋白质每分钟17纳摩尔和1.0毫摩尔。在可比条件下，柠檬酸盐的初始转运速率是糖和氨基酸的5倍。10毫摩尔琥珀酸盐、苹果酸盐、富马酸盐或草酰乙酸盐可使0.1毫摩尔柠檬酸盐和α-酮戊二酸的摄取速率受到超过90%的抑制，这表明刷状缘膜中存在一种高度专门用于肾脏保留三羧酸循环中间产物的转运系统。
