RNA helicase activity associated with the human p68 protein

Nature. 1989 Jun 15;339(6225):562-4. doi: 10.1038/339562a0.


It has been proposed that p68, a nuclear protein of relative molecular mass 68,000, functions in the regulation of cell growth and division. A complementary DNA analysis of the protein has revealed extensive amino-acid sequence homology to the products of a set of genes recently identified in organisms as diverse as Escherichia coli and man, which include the eukaryotic translation initiation factor elF-4A. The protein products of the new gene family have several motifs in common which are thought to be involved in nucleic acid unwinding. As yet, however, only elF-4A, through its effect on RNA, has been shown to possess unwinding activity. Here we report that purified p68 also exhibits RNA-dependent ATPase activity and functions as an RNA helicase in vitro. The protein was first identified by its specific immunological cross reaction with the simian virus 40 large T antigen, the transforming protein of a small DNA tumour virus. Surprisingly, T antigen also has an RNA-unwinding activity: the homology between the two polypeptides, although confined to only a small region resembling the epitope of the cross-reacting antibody (PAb204), should therefore be of functional significance. Furthermore, the RNA-unwinding activity may be involved in the growth-regulating functions of both proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • DEAD-box RNA Helicases
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • In Vitro Techniques
  • Nuclear Proteins / physiology*
  • Protein Kinases*
  • RNA / metabolism*
  • RNA Helicases*
  • RNA Nucleotidyltransferases / metabolism*


  • Nuclear Proteins
  • RNA
  • Protein Kinases
  • RNA Nucleotidyltransferases
  • Adenosine Triphosphatases
  • Ddx5 protein, human
  • DEAD-box RNA Helicases
  • RNA Helicases