Stringer E A, Chaudhuri A, Maitra U
J Biol Chem. 1979 Aug 10;254(15):6845-8.
Eukaryotic initiation factor 2 (eIF-2), which specifically binds Met-tRNAMetf and forms stable ternary complexes with GTP, has been purified from ribosomal salt wash proteins from calf liver. The purified factor exhibits only two polypeptide bands of Mr = 48,000 and 38,000 following electrophoresis in 15% polyacrylamide gels in the presence of sodium dodecyl sulfate. Densitometric tracings show the two polypeptides are present in a molar ratio of 1:1. This suggests a Mr = 86,000 for the native enzyme, a value which agrees with the apparent molecular weight determined by physical methods. Less pure preparations of eIF-2 show additional polypeptide bands, including 50,000- and 46,000-dalton bands, all of which can be removed by further purification without affecting the activity of eIF-2.
真核生物起始因子2（eIF - 2）能特异性结合甲硫氨酰 - tRNAfMet，并与GTP形成稳定的三元复合物，已从小牛肝脏核糖体盐洗蛋白中纯化得到。在十二烷基硫酸钠存在的情况下，经15%聚丙烯酰胺凝胶电泳后，纯化的因子仅显示出两条分子量分别为48,000和38,000的多肽带。光密度扫描显示这两种多肽的摩尔比为1:1。这表明天然酶的分子量为86,000，该值与通过物理方法测定的表观分子量一致。纯度较低的eIF - 2制剂显示出其他多肽带，包括50,000道尔顿和46,000道尔顿的条带，所有这些条带都可以通过进一步纯化去除，而不会影响eIF - 2的活性。
