Jargiello P
Biochim Biophys Acta. 1980 Nov 3;632(4):507-16. doi: 10.1016/0304-4165(80)90327-x.
In variants of the Novikoff hepatoma cell line, the ability to use D-ribose as a carbon source appeared to be due to changes in the expression of ribokinase. Examination of ribokinase activity was prompted by the finding that uptake of radiolabeled ribose was linear for 30 min in six variants but became saturated within 2 min in nine other variants. The linear uptake of ribose was due to a high rate of phosphorylation by ribokinase. Variants which showed linear uptake kinetics had ribokinase levels of 6.8 +/- 1.7 nm/min per mg protein as compared to the parental levels of 0.90 +/- 0.25 nm/min per mg protein. The nine variants which showed saturable uptake kinetics had low parenteal levels of ribokinase. However, these variants showed a change in the subcellular location of that activity. The enzyme was predominantly membrane-associated in both parental cells and high ribokinase variants. In contrast, the low ribokinase variants had a cytoplasmic form of the enzyme. A more general membrane change probably occurred in these variants, since they showed an increased sensitivity to the unrelated membrane reactive compounds, phytohemagglutinin and ouabain.
在诺维科夫肝癌细胞系的变体中，利用D-核糖作为碳源的能力似乎归因于核糖激酶表达的变化。对核糖激酶活性的检测是由以下发现引发的：在六个变体中，放射性标记核糖的摄取在30分钟内呈线性，但在其他九个变体中，在2分钟内就达到了饱和。核糖的线性摄取是由于核糖激酶的高磷酸化速率。表现出线性摄取动力学的变体，其核糖激酶水平为每毫克蛋白质6.8±1.7纳米/分钟，而亲本水平为每毫克蛋白质0.90±0.25纳米/分钟。表现出饱和摄取动力学的九个变体，其亲本核糖激酶水平较低。然而，这些变体在该活性的亚细胞定位上发生了变化。该酶在亲本细胞和高核糖激酶变体中主要与膜相关。相比之下，低核糖激酶变体具有该酶的细胞质形式。这些变体可能发生了更普遍的膜变化，因为它们对无关的膜反应性化合物植物血凝素和哇巴因表现出更高的敏感性。
