Stein W D, Rosengurt E
Biochim Biophys Acta. 1976 Jan 8;419(1):112-9. doi: 10.1016/0005-2736(76)90376-x.
(1) The kinetics of uptake of uridine into 3T3 cells have been measured as a function of concentration in the temperature range 5-37 degrees C, for both quiescent and serum-stimulated cells. (2) The maximun velocity of uridine uptake is increased some ten-fold by adding serum, but the hald-saturation concentration is not systematically affected in this temperature range. (3) A detailed study of the temperature dependence of the maximum velocity of transport in the range 4-43 degrees C shows that the activation energy of uridine transport is not increased following serum activation. (4) The data suggest that any change in membrane fluidity that might occur as a result of serum activation does not in itself lead to a more rapid rate of turn over of the individual uridine carriers. It would appear, rather, that there is an increase in the number of functional uridine carriers.
(1) 已测定在5至37摄氏度温度范围内，静止细胞和血清刺激细胞摄取尿苷进入3T3细胞的动力学与浓度的函数关系。(2) 添加血清可使尿苷摄取的最大速度提高约10倍，但在该温度范围内，半饱和浓度没有系统性变化。(3) 对4至43摄氏度范围内转运最大速度的温度依赖性进行的详细研究表明，血清激活后尿苷转运的活化能并未增加。(4) 数据表明，血清激活可能导致的膜流动性的任何变化本身并不会导致单个尿苷载体的周转速度加快。相反，似乎功能性尿苷载体的数量有所增加。
