title: Class III POU genes: generation of homopolymeric amino acid repeats under GC pressure in mammals.
abstract: The class III POU transcription factor genes play an important role in the nervous system. Comparison of their entire amino acid sequences disclosed a remarkable feature of particular mammalian class III POU genes. Alanine, glycine, and proline repeats were present in the mammalian Brain-1 gene, whereas most of these repeats were absent in the nonmammalian homologue. The mammalian Brain-2 gene had alanine, glycine, proline, and glutamine repeats, which were missing in the nonmammalian homologue. The mammalian Scip gene had alanine, glycine, proline, and histidine repeats, but the nonmammalian homologue completely lacked these repeats. In contrast, the mammalian Brain-4 gene had no amino acid repeats like its nonmammalian homologue. The mammalian genes containing the characteristic amino acid repeats had another feature, higher GC content. We found a positive correlation between the GC content and the amino acid repeat ratio. Those amino acids were encoded by triplet codons with relatively high GC content. These results suggest that the GC pressure has facilitated generation of the homopolymeric amino acid repeats.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sumiyama
authors.forename: K
authors.initials: K
authors.lastname: Washio-Watanabe
authors.forename: N
authors.initials: N
authors.lastname: Saitou
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
authors.forename: S
authors.initials: S
authors.lastname: Ueda
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D012831:Bombyx; D017173:Caenorhabditis elegans; D003062:Codon; D017931:DNA Primers; D004331:Drosophila melanogaster; D019143:Evolution, Molecular; D014644:Genetic Variation; D005998:Glycine; D006801:Humans; D008322:Mammals / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010932:Planarians; D016133:Polymerase Chain Reaction; D011392:Proline; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics*; D014982:Xenopus laevis; D015027:Zebrafish
chemical_list: D003062:Codon; D017931:DNA Primers; D014157:Transcription Factors; D011392:Proline; D000409:Alanine; D005998:Glycine