Studies with cell free systems of protein synthesis have shown that mRNAs are not translated uniformly by ribosomes. In particular the existence of mRNA specific initiation factors which stimulate or inhibit the translation of individual cistrons is now well recognized. This study indicates that the specificity of IF3 for mRNAs actually results from its combination with 'interference' protein factors. These proteins act in the presence of IF3 to stimulate the translation of certain cistrons while inhibiting that of others. The authors isolated three interference factors from E. coli and characterized some of their cistron specificities on MS2 RNA, T4 and T7 early and late mRNAs. These factors can explain the heterogeneity of IF3 toward various mRNA. In vivo variations in the activity of ribosomes can result from changes either in IF3 or in an interference factor.
|Number of pages||21|
|Issue number||180 sup|
|State||Published - 1 Jan 1973|
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