Bascom C C, Sharifi B G, Johnson T C
J Cell Physiol. 1986 Aug;128(2):202-8. doi: 10.1002/jcp.1041280210.
We have isolated from bovine cerebral cortex cells and purified to homogeneity an 18,000 dalton, pl 3.0 sialoglycopeptide that inhibits protein synthesis and DNA synthesis of nontransformed but not transformed cells without affecting uptake of radiolabeled precursors. In this paper, we examine the relationship between the binding of the sialoglycopeptide inhibitor to 3T3 cells and inhibition of protein synthesis. Binding of the sialoglycopeptide to 3T3 cells was rapid at 37 degrees C and reached a maximum at 30 min; the binding at 37 degrees C was shown to be saturable and specific. Scatchard analysis of the binding indicated that 3T3 cells contained about 2 X 10(4) receptors/cell with a dissociation constant of 1.0-1.5 nM. Several lines of evidence indicated that receptor occupancy on 3T3 cells correlated with the protein synthesis inhibitory activity of the sialoglycopeptide. A comparison of the kinetics of inhibitor binding with the kinetics of protein synthesis inhibition demonstrated that binding directly correlated with the inhibition of protein synthesis, concentration-dependent inhibition of protein synthesis directly correlated with concentration-dependent receptor occupancy, and a direct correlation was also observed between the kinetics of inhibitor dissociation from its specific cell surface receptor and the kinetics of recovery from protein synthesis inhibition.
我们已从牛大脑皮层细胞中分离出一种18,000道尔顿、等电点为3.0的唾液酸糖肽，并将其纯化至同质。该肽可抑制未转化细胞而非转化细胞的蛋白质合成和DNA合成，且不影响放射性标记前体的摄取。在本文中，我们研究了唾液酸糖肽抑制剂与3T3细胞的结合及蛋白质合成抑制之间的关系。唾液酸糖肽与3T3细胞的结合在37℃时迅速，30分钟时达到最大值；37℃时的结合表现为可饱和且具有特异性。对结合的Scatchard分析表明，3T3细胞每细胞含有约2×10⁴个受体，解离常数为1.0 - 1.5 nM。多条证据表明，3T3细胞上的受体占据情况与唾液酸糖肽的蛋白质合成抑制活性相关。抑制剂结合动力学与蛋白质合成抑制动力学的比较表明，结合与蛋白质合成抑制直接相关，蛋白质合成的浓度依赖性抑制与浓度依赖性受体占据直接相关，并且在抑制剂从其特异性细胞表面受体解离的动力学与从蛋白质合成抑制中恢复的动力学之间也观察到直接相关性。
