Characterization and Immunolocalization of a Nucleolar Antigen With anti-NOR Serum in HeLa Cells

Exp Cell Res. 1992 Jun;200(2):393-403. doi: 10.1016/0014-4827(92)90187-d.


We have used a serum from a patient with rheumatoid arthritis and found it to immunoblot with a 92- to 88-kDa protein doublet with an isoelectric point of around 7.5 after mono- and two-dimensional electrophoresis in whole HeLa cells. By means of immunofluorescence and immunoelectron microscopy we have found it to specifically react with the nucleolar fibrillar component. After quantitative analysis under the electron microscope, we have demonstrated a similar labeling both in the fibrillar centers and the dense fibrillar component, using two different gold-coupled markers. When transcription was inhibited under physiological conditions (mitosis) or after AMD treatment the antigen remained, as shown by immunoblotting and immunolabeling with anti-NOR serum. These biochemical characteristics, which coincide with those of the ribosomal transcription human upstream binding factor, together with the immunolocalization with anti-NOR serum, allow us to discuss the possible role of these antigens in rDNA transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthritis, Rheumatoid / immunology*
  • Autoantigens / chemistry*
  • Blotting, Western
  • Cell Nucleolus / immunology*
  • Dactinomycin / pharmacology
  • Electrophoresis, Gel, Two-Dimensional
  • Fluorescent Antibody Technique
  • HeLa Cells
  • Humans
  • Isoelectric Point
  • Microscopy, Electron
  • Molecular Weight
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / immunology*
  • Nucleolus Organizer Region / immunology*


  • Autoantigens
  • Nuclear Proteins
  • Dactinomycin