Goldenberg G J, Stein W D
J Supramol Struct. 1978;9(4):489-96. doi: 10.1002/jss.400090404.
The stimulation of uridine uptake, brought about by the addition of serum or insulin to quiescent 3T3 fibroblasts, is associated in the half-saturation concentration of the uridine phosphorylating system for the substrate ATP, with relatively little change in the maximum uptake or in the affinity for uridine. In stimulated cells the Km towards ATP fell in the range 0.053--0.187 mM, while V max was 34 to 52 pmoles/10(6) cells/min. In quiescent cells these values were 2.89--4.22 mM and 74.5--126 pmoles/10(6) cells/min, respectively. No difference was found, however, between the Km's for ATP when phosphorylation of uridine was determined using cell-free extracts prepared from either quiescent cells or from stimulated cells.
向静止的3T3成纤维细胞中添加血清或胰岛素所引起的尿苷摄取刺激，与尿苷磷酸化系统对底物ATP的半饱和浓度相关，而最大摄取量或对尿苷的亲和力变化相对较小。在受刺激的细胞中，对ATP的Km值在0.053 - 0.187 mM范围内，而Vmax为34至52皮摩尔/10(6)个细胞/分钟。在静止细胞中，这些值分别为2.89 - 4.22 mM和74.5 - 126皮摩尔/10(6)个细胞/分钟。然而，当使用从静止细胞或受刺激细胞制备的无细胞提取物测定尿苷磷酸化时，发现对ATP的Km值之间没有差异。
