ZO-1 and cingulin: tight junction proteins with distinct identities and localizations

Am J Physiol. 1989 Oct;257(4 Pt 1):C621-8. doi: 10.1152/ajpcell.1989.257.4.C621.


The relative localization of ZO-1 and cingulin, the only two known components of the tight junction, was compared in Madin-Darby canine kidney (MDCK) cells, chicken small intestine, rat kidney distal convoluted tubule, and a hepatoma cell line. Immunoblot analysis demonstrated that cingulin and ZO-1 are immunologically unrelated and that, in the colon, cingulin is a single polypeptide with a molecular mass of 140 kDa. Immunofluorescent localization of cingulin and ZO-1 in confluent monolayers of MDCK cells showed identical staining patterns. However, subconfluent MDCK cells showed distinct localizations of the two proteins. Both cingulin and ZO-1 were found at the plasma membrane only at areas of cell-cell contact, but cingulin was diffusely distributed within the cytoplasm, whereas ZO-1 showed a more clustered internal arrangement. Cingulin and ZO-1 were identically localized at the plasma membrane of hepatoma tissue culture (HTC) cells at sites of cell-cell contact. In chicken intestine examined at the ultrastructural level, immunogold particles associated with cingulin were found approximately three times farther from the junctional membrane than those affiliated with ZO-1.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Cell Line
  • Chickens
  • Duodenum / ultrastructure
  • Fluorescent Antibody Technique
  • Intercellular Junctions / analysis
  • Intercellular Junctions / ultrastructure*
  • Kidney
  • Kidney Tubules, Distal / ultrastructure
  • Liver Neoplasms, Experimental
  • Membrane Proteins / analysis*
  • Membrane Proteins / immunology
  • Microscopy, Electron
  • Microvilli / ultrastructure
  • Muscle, Smooth / ultrastructure
  • Phosphoproteins / analysis*
  • Phosphoproteins / immunology
  • Rats
  • Zonula Occludens-1 Protein


  • Antibodies, Monoclonal
  • Membrane Proteins
  • Phosphoproteins
  • Tjp1 protein, rat
  • Zonula Occludens-1 Protein