Simple repetitive sequences in the genome: Structure and functional significance

Samir K. Brahmachari, Gopinath Meera, Partha S. Sarkar, Pichumani Balagurumoorthy, Jalaj Tripathi, Sowmya Raghavan, Umesh Shaligram, Shashank Pataskar

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


The current explosion of DNA sequence information has generated increasing evidence for the claim that noncoding repetitive DNA sequences present within and around different genes could play an important role in genetic control processes, although the precise role and mechanism by which these sequences function are poorly understood. Several of the simple repetitive sequences which occur in a large number of loci throughout the human and other eukaryotic genomes satisfy the sequence criteria for forming non‐B DNA structures in vitro. We have summarized some of the features of three different types of simple repeats that highlight the importance of repetitive DNA in the control of gene expression and chromatin organization. (i) (TG/CA)n repeats are widespread and conserved in many loci. These sequences are associated with nucleosomes of varying linker length and may play a role in chromatin organization. These Z‐potential sequences can help absorb superhelical stress during transcription and aid in recombination. (ii) Human telomeric repeat (TTAGGG)n adopts a novel quadruplex structure and exhibits unusual chromatin organization. This unusual structural motif could explain chromosome pairing and stability. (iii) Intragenic amplification of (CTG)n/(CAG)n trinucleotide repeat, which is now known to be associated with several genetic disorders, could down‐regulate gene expression in vivo. The overall implications of these findings vis‐à‐vis repetitive sequences in the genome are summarized.

Original languageEnglish (US)
Pages (from-to)1705-1714
Number of pages10
Issue number1
StatePublished - 1995
Externally publishedYes


  • Genome
  • Nucleosome
  • Repetitive DNA
  • Telomere
  • Triplet repeat
  • Z‐DNA

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry


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