The RNA binding protein La influences both the accuracy and the efficiency of RNA polymerase III transcription in vitro

EMBO J. 1989 Mar;8(3):841-50. doi: 10.1002/j.1460-2075.1989.tb03445.x.

Abstract

The autoantigen La binds the U-rich 3' ends of all nascent RNA polymerase III transcripts. Here, we demonstrate that this abundant nuclear phosphoprotein not only binds these RNAs but appears to be required for their synthesis. HeLa cell extracts immunochemically depleted of La by either patient or mouse monoclonal antibodies lose greater than 99% of their transcription activity on class III genes. The few transcripts synthesized in the absence of La have fewer uridylate residues at their 3' ends than those made in its presence. Reconstitution of La-depleted extracts with biochemically purified HeLa La protein stimulates transcription levels and completely restores transcript length. A model coupling transcription levels to the action of La at the RNA polymerase III termination signal is presented.

Publication types

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

MeSH terms

  • Autoantigens*
  • Carrier Proteins / metabolism
  • DNA-Directed RNA Polymerases / genetics*
  • HeLa Cells / immunology
  • HeLa Cells / metabolism
  • Humans
  • RNA Polymerase III / genetics*
  • RNA-Binding Proteins
  • Ribonucleoproteins*
  • SS-B Antigen
  • Transcription Factors / metabolism
  • Transcription, Genetic*

Substances

  • Autoantigens
  • Carrier Proteins
  • RNA-Binding Proteins
  • Ribonucleoproteins
  • Transcription Factors
  • DNA-Directed RNA Polymerases
  • RNA Polymerase III