Goss D J, Woodley C L, Wahba A J
Biochemistry. 1987 Mar 24;26(6):1551-6. doi: 10.1021/bi00380a009.
The binding of the eucaryotic polypeptide chain initiation factors (eIFs) 4A, 4B, and 4F to poly(1,N6-ethenoadenylic acid) [poly(epsilon A)] was investigated by fluorescence spectroscopy. Competition experiments allowed us to determine the relative affinity of these proteins for mRNA cap analogues and the triplets AUG, GUG, UUU, UAA, and UGA. The salt dependence of eIF-4A binding to poly(epsilon A) and mRNA suggested that the binding was largely electrostatic and was enhanced in the presence of Mg2+ and ATP. The size of the binding site of eIF-4A, eIF-4B, and eIF-4F on poly(epsilon A) was approximately 13, 25, and 35 nucleotides, respectively. Fluorescence studies with the cap analogue 7-methylguanosine triphosphate as well as competition studies with poly(epsilon A) provide further evidence for a direct interaction of eIF-4F with the cap region. There was no evidence that either eIF-4B or eIF-4A bound the mRNA cap directly. In contrast to the other two factors, eIF-4B was found to bind preferentially to AUG, and of all the triplets tested, AUG was the most effective competitor for poly(epsilon A) binding.
通过荧光光谱法研究了真核生物多肽链起始因子（eIFs）4A、4B和4F与聚（1,N6-乙烯腺苷酸）[聚（εA）]的结合。竞争实验使我们能够确定这些蛋白质对mRNA帽类似物以及三联体AUG、GUG、UUU、UAA和UGA的相对亲和力。eIF-4A与聚（εA）和mRNA结合的盐依赖性表明，这种结合在很大程度上是静电作用，并且在Mg2+和ATP存在时会增强。eIF-4A、eIF-4B和eIF-4F在聚（εA）上的结合位点大小分别约为13、25和35个核苷酸。用帽类似物7-甲基鸟苷三磷酸进行的荧光研究以及与聚（εA）的竞争研究为eIF-4F与帽区域的直接相互作用提供了进一步的证据。没有证据表明eIF-4B或eIF-4A直接结合mRNA帽。与其他两个因子不同，发现eIF-4B优先结合AUG，并且在所有测试的三联体中，AUG是聚（εA）结合的最有效竞争者。
