Frolik C A, Dart L L, Meyers C A, Smith D M, Sporn M B
Proc Natl Acad Sci U S A. 1983 Jun;80(12):3676-80. doi: 10.1073/pnas.80.12.3676.
A polypeptide transforming growth factor (TGF) that induces anchorage-dependent rat kidney fibroblasts to grow in soft agar has been isolated from human placenta and purified to homogeneity. This polypeptide is classified as a type beta TGF because it does not compete with epidermal growth factor (EGF) for membrane receptor sites but does require EGF for induction of anchorage-independent growth of indicator cells. Purification of this peptide was achieved by acid/ethanol extraction of the placenta, followed by gel filtration, cation exchange, and HPLC of the acid-soluble proteins. Homogeneity of the TGF-beta from the final column was shown by its constant specific activity and amino acid composition across the peak of soft agar colony-forming activity and by its migration as a single band at Mr 23,000-25,000 on NaDodSO4/polyacrylamide gel electrophoresis. Under reducing conditions, the protein migrated on a gel as a single band at Mr 13,000. The purified placental TGF-beta caused half-maximal growth stimulation of indicator cells in soft agar at 64-72 pg/ml (3 pM) in the presence of EGF at 2 ng/ml (0.34 nM).
一种能诱导贴壁依赖性大鼠肾成纤维细胞在软琼脂中生长的多肽转化生长因子（TGF）已从人胎盘中分离出来并纯化至同质。这种多肽被归类为β型TGF，因为它不与表皮生长因子（EGF）竞争膜受体位点，但确实需要EGF来诱导指示细胞的非贴壁依赖性生长。该肽的纯化是通过对胎盘进行酸/乙醇提取，然后对酸溶性蛋白质进行凝胶过滤、阳离子交换和高效液相色谱来实现的。最终柱上的TGF-β的同质性通过其在软琼脂集落形成活性峰上恒定的比活性和氨基酸组成以及在NaDodSO4/聚丙烯酰胺凝胶电泳上以Mr 23,000 - 25,000的单一条带迁移来显示。在还原条件下，该蛋白质在凝胶上以Mr 13,000的单一条带迁移。在2 ng/ml（0.34 nM）的EGF存在下，纯化的胎盘TGF-β在软琼脂中以64 - 72 pg/ml（3 pM）的浓度引起指示细胞的最大生长刺激的一半。
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