Characterization of a protein in mid-term human amniotic fluid which reacts in the somatomedin-C radioreceptor assay.
Characterization of a protein in mid-term human amniotic fluid which reacts in the somatomedin-C radioreceptor assay.
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中期人羊水中蛋白质的表征，该蛋白质在生长调节素-C 放射受体测定中发生反应。
DOI：
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发表时间：
1977
影响因子：
5.8
通讯作者：
William H. Daughaday
中科院分区：
文献类型：
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作者：
R. Chochinov;I. Mariz;Anthony S. Hajek;William H. Daughaday
羊水中含有胰岛素以外的物质，这些物质在使用人胎盘膜的生长调节素C放射受体测定中发生反应。妊娠中期羊水中与生长调节素C放射受体测定反应的物质在白蛋白从用0.1M NH 4 HCO 3平衡的Sephadex G-150柱中洗脱后稍微洗脱。无论是煮沸，也不处理该馏分与1%的甲酸产生小分子量生长调节素样肽。通过Ultrogel AcA 44在3.1 M NH 4 HCO 3中的凝胶过滤实现生长调节素反应性物质（Sm RM）与白蛋白的分离。活性产物的表观分子量为33，000至35，000道尔顿;通过聚焦测定其等电点在4.1至5.1之间。在生长调节素C放射受体测定中，纯化的羊水蛋白取代了生长调节素C，但在胰岛素放射受体测定中不与胰岛素竞争。Sm RM只产生轻微的刺激人成纤维细胞的胸苷摄取，但在低氧大鼠肋软骨中刺激硫酸盐摄取无活性。在人成纤维细胞培养物中，Sm RM抑制人血清和纯化的大鼠生长调节素诱导的胸苷摄取的刺激。当Sm RM加入到125 I生长调节素C中时，从pH 8.6的凝胶过滤中洗脱的一些放射性转化为分子量约为43，000的复合物。我们的结论是，我们已经从妊娠中期羊水中分离出的材料是一种蛋白质，它可能会结合生长调节素，使其不可用的人胎盘和人成纤维细胞的生长调节素受体。
Amniotic fluid contains materials other than insulin which react in a somatomedin C radioreceptor assay using human placental membranes. The material in mid-gestational amniotic fluid which reacted with the somatomedin C radioreceptor assay eluted slightly after albumin from a Sephadex G-150 column equilibrated with 0.1M NH4HCO3. Neither boiling nor treatment of this fraction with 1% formic acid yielded small molecular weight somatomedin-like peptides. Separation of the somatomedin reactive material (Sm RM) from albumin was achieved by gel filtration through Ultrogel AcA44 in 3.1M NH4HCO3. The active product had an apparent molecular weight of 33,000 to 35,000 Daltons; its isoelectric point determined by focusing was between 4.1 and 5.1. The purified amniotic fluid protein displaced somatomedin C in the somatomedin C radioreceptor assay but did not compete with insulin in the insulin radioreceptor assay. Sm RM produced only a slight stimulation of thymidine uptake in human fibroblasts but was inactive in stimulating sulfate uptake in hypox rat costal cartilage. In human fibroblast cultures Sm RM inhibited the stimulation of thymidine uptake induced by human serum and by purified rat somatomedin. When Sm RM was added to the 125I somatomedin C, some of the radioactivity eluted from gel filtration at pH 8.6 was converted to a molecular weight complex of about 43,000. We conclude that the material which we have isolated from mid-gestational amniotic fluid is a protein which may bind somatomedin and make it unavailable to the somatomedin receptor of human placenta and human fibroblasts.