Notides A C, Lerner N, Hamilton D E
Proc Natl Acad Sci U S A. 1981 Aug;78(8):4926-30. doi: 10.1073/pnas.78.8.4926.
The equilibrium [3H]estradiol binding by the partially purified estrogen receptor from calf uteri was measured at 25 degrees C. The Scatchard plot of the binding data showed a convex curve characteristic of positive cooperativity and a Hill coefficient of 1.58 +/- 0.21, at receptor concentrations of 1 to 10 nM. Below a receptor concentration of approximately 0.3 nM the Scatchard plot approached linearity, suggesting that the cooperative interactions are dependent upon a monomer--dimer equilibrium. Trypsin pretreatment of the receptor resulted in a loss of dimer formation and of the cooperative interactions. The positive cooperative characteristics of the estrogen receptor were shown not to be produced by receptor inactivation, failure to complete the [3H]estradiol--receptor equilibrium reaction, or radioimpurity of the [3H]estradiol. These findings indicate that the activated 5S estrogen receptor is a homodimer and that its formation is associated with a positive cooperative estradiol-binding reaction.
在25摄氏度下测定了从小牛子宫中部分纯化的雌激素受体与[3H]雌二醇的平衡结合。结合数据的Scatchard图显示出正协同性的凸曲线，在受体浓度为1至10 nM时，希尔系数为1.58±0.21。在受体浓度约为0.3 nM以下时，Scatchard图接近线性，表明协同相互作用依赖于单体-二聚体平衡。用胰蛋白酶预处理受体导致二聚体形成和协同相互作用丧失。雌激素受体的正协同特性并非由受体失活、未能完成[3H]雌二醇-受体平衡反应或[3H]雌二醇的放射性杂质所致。这些发现表明，活化的5S雌激素受体是同二聚体，其形成与正协同性雌二醇结合反应相关。
