Rutherford T R, Weatherall D J
Cell. 1979 Feb;16(2):415-23. doi: 10.1016/0092-8674(79)90017-5.
Friend cells of the line Fw are not induced to accumulate substantial amounts of hemoglobin and to become benzidine-positive when treated with butyric acid or other inducers, except in the presence of exogenous hemin. The cells are shown to have a deficiency in heme synthesis since they require exogenous hemin during the period of maximal hemoglobin synthesis; since endogenous heme synthesis cannot be induced to the level found in normal inducible Friend cells, even after hemoglobin synthesis has been induced by hemin and butyric acid and the hemin has then been withdrawn; since they are not inducible for ferrochelatase (heme synthetase) activity; and since they accumulate free globin chains after stimulation with butyric acid in the absence of hemlin. Comparison of globin synthesis and globin mRNA content of the cells shows that globin synthesis is not controlled by the hemin-controlled repressor of protein synthesis (HCR) nor by any specific translational control of globin synthesis by hemlin.
Fw系的Friend细胞在用丁酸或其他诱导剂处理时，不会被诱导积累大量血红蛋白并变成联苯胺阳性，除非存在外源性血红素。这些细胞显示出血红素合成缺陷，因为它们在血红蛋白合成的高峰期需要外源性血红素；因为即使在血红素和丁酸诱导血红蛋白合成后再去除血红素，内源性血红素合成也不能被诱导到正常可诱导的Friend细胞中发现的水平；因为它们的亚铁螯合酶（血红素合成酶）活性不可诱导；并且因为在没有血红素的情况下用丁酸刺激后它们会积累游离珠蛋白链。对这些细胞的珠蛋白合成和珠蛋白mRNA含量的比较表明，珠蛋白合成不受蛋白质合成的血红素控制阻遏物（HCR）控制，也不受血红素对珠蛋白合成的任何特异性翻译控制。
