Specific binding of polypyrimidine tract binding protein and hnRNP A1 to HIV-1 CRS elements

Alexander C. Black, Jie Luo, Susan Chun, Andreas Bakker, John K. Fraser, Joseph D. Rosenblatt

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The human immunodeficiency virus (HIV) Rev and human T-cell leukemia virus (HTLV) Rex proteins regulate viral RNA processing. Both proteins act to overcome the block to viral structural gene expression, at least in part, by reversing the inhibitory effect of intronic RNA sequences, termed cis-acting repressive (CRS) sequences. Using HTLV type II (HTLV-II) as a model, we recently showed that the function of a 5' long terminal repeat (LTR) CRS correlates with in vitro binding by both polypyrimidine tract binding (PTB) protein (also known as hnRNP I) and hnRNP A1 to CRS RNA (1,2). Using radioimmunoprecipitation of proteins ultraviolet (UV) crosslinked to each HIV CRS RNA with monoclonal anti-hnRNP antibodies, we now demonstrate that hnRNP I and hnRNP A1 bind to two different HIV-1 CRS RNAs. In addition, we show that hnRNP I and hnRNP A1 binding to HIV-1 CRS RNAs can be specifically competed by HTLV-II CRS RNAs using electrophoretic mobility shift assay (EMSA)/UV crosslinking assays. Binding by both hnRNP I and hnRNP A1 to HIV-1 and HTLV-II CRS RNAs suggests a role for these proteins in CRS function that may be influenced by the Rev and Rex proteins, respectively.

Original languageEnglish (US)
Pages (from-to)275-285
Number of pages11
JournalVirus Genes
Issue number3
StatePublished - 1996
Externally publishedYes


  • CRS
  • HIV-1
  • hnRNP A1
  • Polypyrimidine tract binding (PTB) protein

ASJC Scopus subject areas

  • Virology
  • Molecular Biology
  • Immunology
  • Applied Microbiology and Biotechnology
  • Genetics


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