Looking for organization patterns of highly expressed genes: Purine-pyrimidine composition of precursor mRNAs

A. Paz, D. Mester, E. Nevo, A. Korol

Research output: Contribution to journalArticlepeer-review


We analyzed precursor messenger RNAs (pre-mRNAs) of 12 eukaryotic species. In each species, three groups of highly expressed genes, ribosomal proteins, heat shock proteins, and amino-acyl tRNA synthetases, were compared with a control group (randomly selected genes). The purine-pyrimidine (R-Y) composition of pre-mRNAs of the three targeted gene groups proved to differ significantly from the control. The exons of the three groups tested have higher purine contents and R-tract abundance and lower abundance of Y-tracts compared to the control (R-tract-tract of sequential purines with Rn ≥ 5; Y-tract-tract of sequential pyrimidines with Yn ≥ 5). In species widely employing "intron definition" in the splicing process, the Y content of introns of the three targeted groups appeared to be higher compared to the control group. Furthermore, in all examined species, the introns of the targeted genes have a lower abundance of R-tracts compared to the control. We hypothesized that the R-Y composition of the targeted gene groups contributes to high rate and efficiency of both splicing and translation, in addition to the mRNA coding role. This is presumably achieved by (1) reducing the possibility of the formation of secondary structures in the mRNA, (2) using the R-tracts and R-biased sequences as exonic splicing enhancers, (3) lowering the amount of targets for pyrimidine tract binding protein in the exons, and (4) reducing the amount of target sequences for binding of serine/arginine-rich (SR) proteins in the introns, thereby allowing SR proteins to bind to proper (exonic) targets.

Original languageEnglish
Pages (from-to)248-260
Number of pages13
JournalJournal of Molecular Evolution
Issue number2
StatePublished - Feb 2007


  • Exon definition
  • Highly expressed genes
  • Intron definition
  • Purine tracts
  • Pyrimidine tracts
  • Splicing efficiency

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics


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