The Mutation of mRNA Translation Initiation Region Influences Gene Translation

In order to investigate the relationship between the structure of the mRNA translation initiation region (TIR) and gene expression, We mutated multiple sites of the 5' end of IFN-alpha8 and GM-CSF genes by site-directed mutagenesis without changing their amino acid sequences. SDS-PAGE showed that the protein products of mutated genes increased greatly in recombinant clones, as compared with their native genes. RNA dot blot revealed that the difference of their corresponding amount of mRNA transcribed between the native and the mutated genes was negligible. These results imply that the elevated expressions are attributed mainly to increased translation level. The prediction of mRNA secondary structure suggests that the delta G of TIR may have close relations to the expression level.