Murthy G S, Schellenberg C, Friesen H G
Endocrinology. 1982 Dec;111(6):2117-24. doi: 10.1210/endo-111-6-2117.
Bovine placental lactogen (bPL) has been purified to homogeneity from bovine placental tissue. A radioreceptor assay (RRA), using a pregnant rabbit liver membrane fraction and human GH (hGH) as standard and tracer, was employed to monitor hormonal activity during the purification. The apparent molecular weight of bPL is approximately 30,000-32,000 as determined by analytical sodium dodecyl sulfate polyacrylamide gel electrophoresis. Somewhat larger estimates were obtained upon Sephadex gel filtration columns. The isoelectric point of the purified hormone as determined by analytical polyacrylamide gel isoelectric focusing is 5.5. The binding and displacement curves of radioiodinated bPL and hGH in the RRA for GH are superimposable, whereas the displacement curve of bPL in the RRA using the particulate fraction of a pregnant rat liver homogenate is parallel to the ovine PRL standards. Purified bPL is capable of modulating hGH-specific receptor sites in cultured human IM-9 lymphocytes. Stimulation of the growth of quiescent NB2 node lymphoma cells in culture demonstrates that bPL and bovine PRL are equipotent in this bioassay.
牛胎盘催乳素（bPL）已从牛胎盘组织中纯化至同质状态。在纯化过程中，采用以妊娠兔肝膜部分为受体、人生长激素（hGH）为标准品和示踪剂的放射受体分析法（RRA）来监测激素活性。通过分析型十二烷基硫酸钠聚丙烯酰胺凝胶电泳测定，bPL的表观分子量约为30,000 - 32,000。在葡聚糖凝胶过滤柱上得到的估计值略大一些。通过分析型聚丙烯酰胺凝胶等电聚焦测定，纯化激素的等电点为5.5。在生长激素的RRA中，放射性碘化bPL和hGH的结合及置换曲线是可叠加的，而在使用妊娠大鼠肝匀浆颗粒部分的RRA中，bPL的置换曲线与绵羊催乳素标准品平行。纯化的bPL能够调节培养的人IM - 9淋巴细胞中hGH特异性受体位点。培养中对静止的NB2淋巴结淋巴瘤细胞生长的刺激表明，在该生物测定中bPL和牛催乳素具有同等效力。
