Identification of a long stretch of homopurine.homopyrimidine sequence in a cluster of retroposons in the human genome

J Mol Biol. 1990 Apr 5;212(3):453-9. doi: 10.1016/0022-2836(90)90324-F.


A cluster of nine retroposons of four different types in a 6221 base EcoRI DNA fragment was isolated from a human fetal liver genomic library using a human nucleophosmin (B23) cDNA as a probe. These retroposons are: (1) a solitary HERV-K long terminal repeat upstream from; (2) a nucleophosmin processed pseudogene; (3) six Alu repeated sequences interspersed in both directions; and (4) a truncated Kpn repeated sequence integrated by an Alu monomer and the HERV-K long terminal repeat. Sequence analysis shows that the nucleophosmin pseudogene contains a long stretch (135 base-pairs) of homopurine.homopyrimidine (Pur.Pyr) sequence. S1 and P1 nuclease digestion indicated that this sequence was able to adopt a non-B-DNA triplex structure under either acidic or neutral conditions. This finding is the first example of the association of a potential DNA triplex structure with a cluster of retroposons.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • DNA / genetics
  • DNA Transposable Elements*
  • Genes
  • Humans
  • Molecular Sequence Data
  • Nuclear Proteins / genetics*
  • Nucleophosmin
  • Pseudogenes*
  • Purine Nucleotides
  • Pyrimidine Nucleotides
  • Repetitive Sequences, Nucleic Acid*
  • Restriction Mapping


  • DNA Transposable Elements
  • NPM1 protein, human
  • Nuclear Proteins
  • Purine Nucleotides
  • Pyrimidine Nucleotides
  • Nucleophosmin
  • DNA