We analyzed occurrences of bases in 20,352 introns, exons of 25,574 protein-coding genes, and among the three codon positions in the protein-coding sequences. The nucleotide sequences originated from the whole spectrum of organisms from bacteria to primates. The analysis revealed the following: (1) In most exons, adenine dominates over thymine. In other words, adenine and thymine are distributed in an asymmetric way between the exon and the complementary strand, and the coding sequence is mostly located in the adenine-rich strand. (2) Thymine dominates over adenine not only in the strand complementary to the exon but also in introns. (3) A general bias is further revealed in the distribution of adenine and thymine among the three codon positions in the exons, where adenine dominates over thymine in the second and mainly the first codon position while the reverse holds in the third codon position. The product (A1/T1)x(A2/T2)x(T3/A3) is smaller than one in only a few analyzed genes.

Institute of Biophysics Academy of Sciences of the Czech Republic Brno

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Proc Natl Acad Sci U S A. 1981 Mar;78(3):1596-600 PubMed

Nucleic Acids Res. 1987 Feb 11;15(3):1281-95 PubMed

Science. 1993 Jul 30;261(5121):598-600 PubMed

Nucleic Acids Res. 1986 Aug 26;14(16):6345-55 PubMed

J Biomol Struct Dyn. 1992 Dec;10(3):455-64 PubMed

Mol Microbiol. 1991 Dec;5(12):2861-7 PubMed

J Mol Biol. 1994 Jan 7;235(1):389-95 PubMed

Biochem Biophys Res Commun. 1986 Sep 30;139(3):1094-7 PubMed

Nature. 1987 May 7-13;327(6117):20 PubMed

Nucleic Acids Res. 1991 Apr 25;19 Suppl:1981-6 PubMed

Proc Natl Acad Sci U S A. 1966 Apr;55(4):966-74 PubMed

Biochemistry. 1983 Sep 13;22(19):4518-26 PubMed

FEBS Lett. 1992 Jun 29;305(2):163-5 PubMed

Orig Life Evol Biosph. 1985;16(1):69-79 PubMed

J Mol Biol. 1987 Apr 20;194(4):643-52 PubMed

J Mol Evol. 1978 Aug 2;11(3):199-210 PubMed

Nucleic Acids Res. 1993 May 11;21(9):2193-9 PubMed

Mol Gen Genet. 1987 Dec;210(2):314-22 PubMed

J Biol Chem. 1987 May 15;262(14):6864-70 PubMed

Proc Natl Acad Sci U S A. 1992 May 1;89(9):3780-4 PubMed

Genomics. 1992 Aug;13(4):1056-64 PubMed

J Mol Biol. 1992 Dec 20;228(4):1124-36 PubMed

Orig Life Evol Biosph. 1985;16(2):157-64 PubMed

Nucleic Acids Res. 1992 Dec 25;20(24):6441-50 PubMed

J Mol Evol. 1993 Dec;37(6):583-9 PubMed

J Mol Biol. 1993 Mar 5;230(1):51-6 PubMed

Biochim Biophys Acta. 1989 Dec 22;1009(3):280-2 PubMed

Genetics. 1992 Apr;130(4):855-64 PubMed

J Theor Biol. 1988 Nov 8;135(1):125-6 PubMed

Gene. 1987;52(1):103-9 PubMed

Biosystems. 1989;22(3):177-87 PubMed

Biochim Biophys Acta. 1966 May 19;119(2):421-4 PubMed

Nucleic Acids Res. 1993 Jul 1;21(13):2967-71 PubMed

J Theor Biol. 1985 Oct 7;116(3):343-8 PubMed

Mol Biol Evol. 1985 Jan;2(1):13-34 PubMed

Mosaic structure of the DNA molecules of the human chromosomes 21 and 22