title: Accumulation of GC donor splice signals in mammals.
abstract: The GT dinucleotide in the first two intron positions is the most conserved element of the U2 donor splice signals. However, in a small fraction of donor sites, GT is replaced by GC. A substantial enrichment of GC in donor sites of alternatively spliced genes has been observed previously in human, nematode and Arabidopsis, suggesting that GC signals are important for regulation of alternative splicing. We used parsimony analysis to reconstruct evolution of donor splice sites and inferred 298 GT > GC conversion events compared to 40 GC > GT conversion events in primate and rodent genomes. Thus, there was substantive accumulation of GC donor splice sites during the evolution of mammals. Accumulation of GC sites might have been driven by selection for alternative splicing.
  
  
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  This article was reviewed by Jerzy Jurka and Anton Nekrutenko. For the full reviews, please go to the Reviewers' Reports section.
authors.affiliation: Loyola University Medical Center, 2160 S. First Ave., Maywood, IL, 60153, USA. atchourbanov@lumc.edu
authors.forename: Alexander
authors.initials: A
authors.lastname: Churbanov
authors.forename: Stephen
authors.initials: S
authors.lastname: Winters-Hilt
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Igor B
authors.initials: IB
authors.lastname: Rogozin
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D002417:Cattle; D017124:Conserved Sequence; D018900:Dinucleotide Repeats / Q000235:genetics*; D004285:Dogs; D019143:Evolution, Molecular; D006801:Humans; D007438:Introns / Q000235:genetics; D008253:Macaca mulatta; D008322:Mammals / Q000235:genetics*; D051379:Mice; D022821:RNA Splice Sites / Q000235:genetics*; D051381:Rats
chemical_list: D022821:RNA Splice Sites