EVALUATING THE CONTRIBUTION OF POST-TRANSCRIPTIONAL PROCESSING TO DIFFERENTIAL GENE-EXPRESSION

Differential gene expression largely depends upon the attainment of different concentrations of individual mRNAs. This paper formulates a simple testable model of mRNA metabolism that allows the quantitative evaluation of the roles of transcription, posttranscriptional processing, and mRNA degradation in the attainment of differing concentrations of individual mRNAs. Application of this model to available data suggests that the large differences in the concentrations of individual mRNAs result from a combination of 10- to 20-fold differences in rates of transcription, 3- to 10-fold differences in rates of mRNA degradation, and 2- to 3-fold differences in the efficiencies of posttranscriptional processing. The calculations suggest that the rates of both transcription and posttranscriptional processing for abundant cytoplasmic mRNAs are significantly higher than for rare mRNAs. © 1979.