Bommer U A, Henske A, Bielka H
Acta Biol Med Ger. 1978;37(9):1363-76.
A Met-tRNAf binding factor (IF-2) from the microsomal fraction of rat liver and rat hepatoma ascites cells was partially purified by ammonium sulphate fractionation, DEAE-cellulose and phosphocellulose chromatography. The factor binds [3H]Met-tRNAf only in the presence of either GTP or GMPPCP. Maximal binding takes place at 37 degrees C and in the absence of Mg++. The factor is specific for Met-tRNAf and does not bind Phe-tRNA from rat liver or from E. coli. The ternary complex [Met-tRNAf . IF-2 . GTP1 binds to 40 S ribosomal subunits from rat liver in the absence of mRNA or poly(A, G, U) without GTP hydrolysis. GDP as well as aurintricarboxylic acid inhibit the ternary complex formation. Both factors are rapidly inactivated by N-ethylmaleimide treatment and by preincubation at 45 degrees C. Heat inactivation is partially prevented by GTP and GDP. With regard to the functional properties there are no significant differences between IF-2 from normal liver and hepatoma cells. On the other hand heat denaturation compared to the rat liver factor, which may be due to differences in contaminating proteins.
通过硫酸铵分级分离、DEAE - 纤维素和磷酸纤维素层析，对来自大鼠肝脏微粒体部分和大鼠肝癌腹水细胞的甲硫氨酰 - tRNAf结合因子（IF - 2）进行了部分纯化。该因子仅在存在GTP或GMPPCP时才结合[3H]甲硫氨酰 - tRNAf。最大结合发生在37℃且不存在Mg++的情况下。该因子对甲硫氨酰 - tRNAf具有特异性，不结合来自大鼠肝脏或大肠杆菌的苯丙氨酰 - tRNA。三元复合物[甲硫氨酰 - tRNAf·IF - 2·GTP]在不存在mRNA或聚（A，G，U）且不发生GTP水解的情况下与来自大鼠肝脏的40S核糖体亚基结合。GDP以及金精三羧酸抑制三元复合物的形成。这两种因子通过N - 乙基马来酰亚胺处理和在45℃预孵育会迅速失活。GTP和GDP可部分防止热失活。就功能特性而言，正常肝脏和肝癌细胞的IF - 2之间没有显著差异。另一方面，与大鼠肝脏因子相比存在热变性，这可能是由于污染蛋白质的差异所致。
