Filipowicz W, Furuichi Y, Sierra J M, Muthukrishnan S, Shatkin A J, Ochoa S
Proc Natl Acad Sci U S A. 1976 May;73(5):1559-63. doi: 10.1073/pnas.73.5.1559.
Ribosomal salt washes of Artemia salina embryos contain a protein(s) that binds [3H]m7GpppGpC and [3H]m7GpppGmpC, as measured by retention on nitrocellulose membrane filters. These oligonucleotides correspond in structure to the methylated 5'-terminal sequences (caps) present in many eukaryotic mRNAs. The cap binding protein does not bind the unmethylated counterparts of caps, e.g., [32P]GpppGpCp, or a derivative of m7GpppGmpC containing ring-opened m7G. None of the purified initiation factors IF-MP, IF-M2A, IF-M2B, IF-M3, or IF-MI binds the m7G-containing oligonucleotides.
通过硝酸纤维素膜过滤器上的保留情况测定,卤虫胚胎的核糖体盐洗物中含有一种能结合[3H]m7GpppGpC和[3H]m7GpppGmpC的蛋白质。这些寡核苷酸在结构上与许多真核生物mRNA中存在的甲基化5'-末端序列(帽结构)相对应。帽结合蛋白不结合帽结构的未甲基化对应物,例如[32P]GpppGpCp,或含有开环m7G的m7GpppGmpC衍生物。纯化的起始因子IF-MP、IF-M2A、IF-M2B、IF-M3或IF-MI均不结合含m7G的寡核苷酸。