In genes alg5, alg8 and swp1 of Saccharomyces cerevisiae, gpt of Schizosaccharomyces pombe and human gene alg6, encoding the dolichol cycle enzymes, a mirror type internal symmetry was found. The symmetry was detected in both complete nucleotide sequences and sequences of the first, second and third nucleotide bases of codons. In the encoding gene regions the density of single- and double-point centres of the internal symmetry for sequences of the second bases was higher in comparison with the sequences of the first and third bases of codons, whereas in the noncoding regions degrees of symmetry of the first, second and third bases sequences did not differ significantly. A clear positive correlation was revealed in the internal symmetry distribution in the second base sequences of codons in genes, on the one hand, and in the gene encoded amino acid sequences, on the other hand. The maximum internal symmetry of gene segments encoding the functionally important regions of proteins was found at the level of the second base sequences. The obtained results corroborate a hypothesis about the determining role of the second bases of codons in encoding amino acid residues. The investigation of internal symmetry in nucleotide sequences has first shown the existence of internal symmetry at the level of gene primary structure.

• PMID: 11517666
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Journal Article

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Shpakov AO

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