Trypanosoma brucei poly(A) binding protein I cDNA cloning, expression, and binding to 5 untranslated region sequence elements

Mol Biochem Parasitol. 1999 Jan 5;98(1):117-29. doi: 10.1016/s0166-6851(98)00156-x.


Poly(A) binding protein I (PABPI) is a highly conserved eukaryotic protein that binds mRNA poly(A) tails and functions in the regulation of translational efficiency and mRNA stability. As a first step in our investigation of the role(s) of mRNA poly(A) tails in posttranscriptional gene regulation in Trypanosoma brucei, we have cloned the cDNA encoding PABPI from this organism. The cDNA predicts a protein homologous to PABPI from other organisms and displaying conserved features of these proteins, including four RNA binding domains that span the N-terminal two-thirds of the protein. Comparison of northern blot data with the cDNA sequence indicates an unusually long 3' untranslated region (UTR) of approximately three kilobases. The 5 UTR contains both A-rich and AU repeat regions, the former being a ubiquitous property of PABPI 5' UTRs. T. brucei PABPI, expressed as a glutathione-S-transferase fusion protein, bound to RNA comprised of its full length 5' UTR in UV cross-linking experiments. This suggests that PABPI may play an autoregulatory role in its own expression. Competition experiments indicate that the A-rich region, but not the AU repeats, are involved in this binding.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 5' Untranslated Regions*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Binding Sites
  • Binding, Competitive
  • Cloning, Molecular
  • Conserved Sequence
  • Gene Expression Regulation
  • Molecular Sequence Data
  • Poly(A)-Binding Proteins
  • Protein Binding
  • Protein Biosynthesis
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Trypanosoma brucei brucei / genetics*


  • 5' Untranslated Regions
  • Poly(A)-Binding Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins

Associated data

  • GENBANK/AF042190