Gross M
Biochim Biophys Acta. 1978 Oct 24;520(3):642-9. doi: 10.1016/0005-2787(78)90149-1.
Previous studies have demonstrated that the hemin-controlled translational repressor (HCR), a high molecular weight protein inhibitor of polypeptide chain initiation in rabbit reticulocyte lysate, is formed from a presynthesized prorepressor over a period of 12--18 h in three stages denoted reversible, intermediate, and irreversible. The prorepressor can, however, be completely converted to irreversible HCR within 2 min by incubation with such sulfhydryl reagents as N-ethylmaleimide. The results in this report demonstrate that dithiothreitol, which stabilizes thiol groups, will, like hemin, prevent the conversion of the prorepressor to HCR and will inactivate reversible HCR. Unlike hemin, dithiothreitol also inactives the intermediate form of HCR. Neither dithiothreitol nor hemin has any effect on the activity of irreversible HCR. Since the prorepressor used in these experiments had been separated from the supernatant factor (a soluble protein that reverses the inhibition of protein synthesis due to HCR), the effect of dithiothreitol and of hemin is independent of this factor and may be mediated by direct interaction with the prorepressor and HCR. Dithioerythritol, the erythro isomer of dithiothreitol, is as effective as dithiothreitol in preventing the formation of HCR, whereas glutathione and beta-mercaptoethanol have little or no effect.
先前的研究表明，血红素控制的翻译阻遏物（HCR）是兔网织红细胞裂解液中一种高分子量的多肽链起始蛋白抑制剂，它由预先合成的前阻遏物在12 - 18小时内分三个阶段形成，分别为可逆阶段、中间阶段和不可逆阶段。然而，通过与诸如N - 乙基马来酰亚胺等巯基试剂孵育，前阻遏物可在2分钟内完全转化为不可逆的HCR。本报告中的结果表明，能稳定巯基的二硫苏糖醇，与血红素一样，会阻止前阻遏物转化为HCR，并使可逆的HCR失活。与血红素不同的是，二硫苏糖醇还会使HCR的中间形式失活。二硫苏糖醇和血红素对不可逆HCR的活性均无任何影响。由于这些实验中使用的前阻遏物已与上清因子（一种可逆转因HCR导致的蛋白质合成抑制的可溶性蛋白质）分离，二硫苏糖醇和血红素的作用独立于该因子，可能是通过与前阻遏物和HCR的直接相互作用介导的。二硫苏糖醇的赤藓糖异构体二硫赤藓糖醇在阻止HCR形成方面与二硫苏糖醇同样有效，而谷胱甘肽和β - 巯基乙醇几乎没有影响或没有影响。
