THE TYPE-II INSULIN-LIKE GROWTH-FACTOR (IGF) RECEPTOR HAS LOW AFFINITY FOR IGF-I ANALOGS - PLEIOTYPIC ACTIONS OF IGFS ON MYOBLASTS ARE APPARENTLY MEDIATED BY THE TYPE-I RECEPTOR
THE TYPE-II INSULIN-LIKE GROWTH-FACTOR (IGF) RECEPTOR HAS LOW AFFINITY FOR IGF-I ANALOGS - PLEIOTYPIC ACTIONS OF IGFS ON MYOBLASTS ARE APPARENTLY MEDIATED BY THE TYPE-I RECEPTOR
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DOI：
10.1210/endo-120-1-115
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发表时间：
1987-01-01
期刊：
影响因子：
4.8
通讯作者：
FLORINI, JR
中科院分区：
文献类型：
--
作者：
EWTON, DZ;FALEN, SL;FLORINI, JR
我们的特点结合和几个行动的生长调节素[胰岛素样生长因子I和II（IGF-I和IGF-II）]对L 6成肌细胞。IGF-I和IGF-II都是氨基酸摄取、细胞增殖和分化的强效刺激剂;它们还抑制这些细胞中的蛋白质降解。在所有测量中，相对效力为IGF-I > IGF-II >胰岛素。两种重组DNA产生的IGF-I类似物，（Thr 59）IGF-I和（N-Met）IGF-I，在所有四种测定中与天然IGF-I一样具有活性。然而，当125 I标记的激素用于研究结合IGF受体时，天然和重组IGF-I分子之间存在显著差异。两者均被I型受体（巯基还原时解离的350 K分子）显著结合，但重组类似物与II型受体（还原时不解离的220 K分子）几乎没有交叉反应性。因此，天然IGF-I和其重组DNA产生的类似物的相等活性加上IGF-I的更高效力（与IGF-II相比）表明II型受体在L 6成肌细胞中研究的生长调节素的四种作用中起很小或没有作用。
We have characterized binding and several actions of the somatomedins [insulin-like growth factors I and II (IGF-I and IGF-II)] on L6 myoblasts. Both IGF-I and IGF-II are potent stimulators of amino acid uptake, cell proliferation, and differentiation; they also suppress protein degradation in these cells. In all measurements, the relative potencies are IGF-I > IGF-II > insulin. Two recombinant DNA-produced analogs of IGF-I, (Thr59)IGF-I and (N-Met)IGF-I, were as active as native IGF-I in all four assays. However, when 125I-labeled hormones were used for studies of binding to IGF receptors, there was a striking difference between the native and recombinant IGF-I molecules. Both were bound significantly by the type I receptor (a 350K molecule that is dissociated upon sulfhydryl reduction), but the recombinant analogs exhibited little cross-reactivity with the type II receptor (a 220K molecule that is not dissociated by reduction). Thus, the equal activity of native IGF-I and its recombinant DNA-produced analogs coupled with the higher potency of IGF-I (compared to IGF-II) suggest that the type II receptor plays little or no role in the four actions of the somatomedins studied in L6 myoblasts.