Nadal C, Boffa G A
Cell Tissue Kinet. 1975 Jul;8(4):297-305. doi: 10.1111/j.1365-2184.1975.tb01495.x.
Rat hepatocytes are responsive to a serum factor inhibiting their progression through the cell cycle from the late G1 phase to the S phase. After fractionation of normal adult rat serum by two chromatographic steps on DEAE cellulose and sephadex gel filtration, the inhibitory activity was linked to proteins having a high electronegative charge and of apparent high molecular weight. Polyacrylamide gel electrophoretic analysis of active fraction showed that the alpha1 macroglobulin was its main component. Male and female baby rats were sensitive to the inhibitory factor from normal rats. Contrary to the normal adult rat serum the whole hepatectomized adult rat serum did not exhibit any ingibitory activity on the G1-S transition. However, two components having antagonist activities: an alpha1 globulin and a gamma globulin, were separated by chromatographic procedures from hepatectomized rat serum. (a) The alpha1 globulin showed an inhibitory activity. It had an apparent molecular weight lower than that found in normal rats. Its activity was sex related: only male baby rats were responsive. (b) The factor present in the gamma globulin fraction was found to be antagonistic to the alpha1 globulin factor. Its occurrence after hepatectomy explains the absence of inhibitory activity in the serum of hepatectomized rats.
大鼠肝细胞对一种血清因子有反应，该因子可抑制其从细胞周期的G1期晚期进入S期。通过在DEAE纤维素和葡聚糖凝胶过滤上进行两步色谱分离法对正常成年大鼠血清进行分级分离后，抑制活性与具有高负电荷和明显高分子量的蛋白质相关。对活性组分进行聚丙烯酰胺凝胶电泳分析表明，α1巨球蛋白是其主要成分。雄性和雌性幼鼠对正常大鼠的抑制因子敏感。与正常成年大鼠血清相反，全肝切除的成年大鼠血清对G1-S期转变没有表现出任何抑制活性。然而，通过色谱法从肝切除大鼠血清中分离出两种具有拮抗活性的成分：一种α1球蛋白和一种γ球蛋白。(a)α1球蛋白表现出抑制活性。其表观分子量低于正常大鼠中的分子量。其活性与性别有关：只有雄性幼鼠有反应。(b)发现γ球蛋白组分中的因子对α1球蛋白因子具有拮抗作用。肝切除后它的出现解释了肝切除大鼠血清中缺乏抑制活性的原因。
