Anzano M A, Roberts A B, Smith J M, Sporn M B, De Larco J E
Proc Natl Acad Sci U S A. 1983 Oct;80(20):6264-8. doi: 10.1073/pnas.80.20.6264.
Sarcoma growth factor (SGF) derived from conditioned medium of Moloney sarcoma virus-transformed cells and partially purified by gel filtration (crude SGF) has been characterized by its ability both to compete with epidermal growth factor (EGF) for binding to membrane receptors and to induce anchorage-independent growth of untransformed cells. We now show that further purification of crude SGF by reverse-phase HPLC on muBondapak C18 and CN columns at pH 2 resolves it into two distinctly different polypeptides, which we call types alpha and beta transforming growth factors (TGFs). Type alpha TGF (TGF-alpha), but not type beta TGF (TGF-beta), competes for binding to the EGF receptor and induces the formation of small colonies (1,000-2,000 micron2) of normal rat kidney cells in soft agar. Both TGF-beta and EGF or TGF-alpha must be present in order to induce the formation of large colonies (7,000-15,000 micron2). Based on EGF competing equivalents as determined from a radioreceptor assay with 125I-labeled EGF in normal rat kidney cells, the relative ability of EGF and TGF-alpha to potentiate TGF-beta-dependent colony formation is in the order conditioned-medium TGF-alpha greater than EGF greater than intracellular TGF-alpha. Suboptimal concentrations of the same polypeptides give additive potentiation of the TGF-beta-dependent colony-forming response; saturating levels potentiate a similar maximum response whether used alone or in various combinations. The data indicate that the EGF-competing activity of crude SGF is due to its TGF-alpha component alone, whereas the soft-agar colony-forming activity is due to the combined action of two distinct polypeptides, TGF-alpha and TGF-beta.
从莫洛尼肉瘤病毒转化细胞的条件培养基中获得并经凝胶过滤部分纯化的肉瘤生长因子（SGF，粗制SGF），其特性在于既能与表皮生长因子（EGF）竞争结合膜受体，又能诱导未转化细胞的锚定非依赖性生长。我们现在表明，在pH 2条件下，通过在μBondapak C18和CN柱上进行反相高效液相色谱对粗制SGF进一步纯化，可将其分离为两种明显不同的多肽，我们将其称为α型和β型转化生长因子（TGFs）。α型TGF（TGF-α）而非β型TGF（TGF-β）能竞争结合EGF受体，并在软琼脂中诱导正常大鼠肾细胞形成小菌落（1000 - 2000平方微米）。为了诱导形成大菌落（7000 - 15000平方微米），必须同时存在TGF-β和EGF或TGF-α。根据在正常大鼠肾细胞中用125I标记的EGF进行放射受体测定所确定的EGF竞争等效物，EGF和TGF-α增强TGF-β依赖性菌落形成的相对能力顺序为：条件培养基中的TGF-α＞EGF＞细胞内TGF-α。相同多肽的次优浓度对TGF-β依赖性菌落形成反应具有累加增强作用；饱和水平无论单独使用还是以各种组合使用，都能增强类似的最大反应。数据表明，粗制SGF的EGF竞争活性仅归因于其TGF-α成分，而软琼脂菌落形成活性则归因于两种不同多肽TGF-α和TGF-β的联合作用。
