title: Significance of the purine-pyrimidine motif present in most gene groups.
abstract: The probability of the sequence YRY(Ni)YRY occurring most frequently with the same i value in seven out of nine gene classes is reassessed and found to be about 1.3 X 10(-8), more than 4000 times greater than the value calculated by Arquès & Michel (1987), but still much too small for chance to be a reasonable explanation for the observation. Even if the sequence YRYNNNNNNYRY were very frequent in the most primitive genes, it would not have survived in a recognizable form to the present day if it were selectively neutral. However, if it is selectively favoured one would expect it to exist regardless of whether it was present in primitive genes.
authors.affiliation: Centre de Biochimie et de Biologie Moléculaire, Centre National de la Recherche Scientifique, Marseille, France.
authors.forename: A
authors.initials: A
authors.lastname: Cornish-Bowden
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D005796:Genes; D011336:Probability; D011685:Purine Nucleotides / Q000235:genetics*; D011742:Pyrimidine Nucleotides / Q000235:genetics*
chemical_list: D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides