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Immunogenetics

, Volume 47, Issue 3, pp 246–255 | Cite as

A new repetitive sequence uniquely present in the decay-accelerating factor genes

  • Mayumi Nonaka
  • Masaru Nonaka
  • Osamu Takenaka
  • Noriko Okada
  • H. Okada
ORIGINAL PAPER

Abstract

 The decay-accelerating factor (DAF, CD55) protects cells from autologous complement attack on self cell membranes. We have previously reported that the seventh exon encoding the serine/threonine-rich(S/T)-abc region of the guinea pig DAF gene is composed of five homologous repeats of about 51 base pairs, and that differential usage of these repeats produces the various lengths observed in the S/T region of guinea pig DAF. In this study, we found that the seventh intron of the guinea pig DAF gene was wholly composed of 18 tandem repeats homologous to the repeating unit of the S/T-abc exon. This type of repetitive structure, although the number of repeats was variable, was also found in the corresponding exons and introns of all DAF genes of other species so far tested including human and seven other primates and mouse, in which alternative splicing in this region has not been found. This suggested that generation of the repetitive sequences spanning the exon and intron regions had occurred before the diversification of these species. In addition, all the intron sequences of the tested DAF genes had no stop codon when they were presumably translated in the same reading frame as the seventh and eighth exons, except for that of one of two duplicated mouse DAF genes. These findings and significant interspecies identities of the intron sequence suggest that the intron sequence conceivably could be translated in some tissues and/or in some stages of development although to date we have not yet succeeded in detecting mRNA for this region.

Key words Complement Decay-accelerating factor Repetitive sequence Gene structure Serine/threonine-rich region 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Mayumi Nonaka
    • 1
  • Masaru Nonaka
    • 2
  • Osamu Takenaka
    • 3
  • Noriko Okada
    • 1
  • H. Okada
    • 1
  1. 1.Department of Molecular Biology, Nagoya City University School of Medicine, Mizuho-ku, Nagoya 467, JapanJP
  2. 2.Department of Biochemistry, Nagoya City University School of Medicine, Mizuho-ku, Nagoya 467, JapanJP
  3. 3.Primate Research Institute, Kyoto University, Inuyama 484, JapanJP

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