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Identification of a 160-kDa polypeptide that binds to the tight junction protein ZO-1

B Gumbiner1, T Lowenkopf, D Apatira

  • 1Department of Pharmacology, University of California School of Medicine, San Francisco 94143.

Proceedings of the National Academy of Sciences of the United States of America
|April 15, 1991
PubMed

Insights

Researchers identified a novel 160-kDa polypeptide that binds to Zonula Occludens-1 (ZO-1) protein. This new protein is a distinct cytoplasmic component of the epithelial tight junction.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Zonula Occludens-1 (ZO-1) is a peripheral membrane protein crucial for epithelial tight junctions.
  • The interaction of ZO-1 with other tight junction proteins is not fully understood.

Purpose of the Study:

  • To identify and characterize novel proteins that interact with ZO-1.
  • To investigate the role of these interacting proteins in tight junction structure and function.

Main Methods:

  • Co-immunoprecipitation of ZO-1 and interacting proteins from Madin-Darby canine kidney (MDCK) cell extracts.
  • Western blotting and peptide mapping to confirm the identity and distinctness of the interacting polypeptide.
  • Cell surface labeling and high salt extraction to determine protein localization and membrane association.

Main Results:

  • A 160-kDa polypeptide was identified that co-immunoprecipitates with ZO-1.
  • The 160-kDa polypeptide is distinct from ZO-1, lacking shared epitopes and exhibiting a different peptide map.
  • Both ZO-1 and the 160-kDa polypeptide are peripheral, cytoplasmic membrane proteins and exhibit similar turnover kinetics.

Conclusions:

  • The 160-kDa polypeptide is a novel component of the epithelial tight junction.
  • This finding expands our understanding of the molecular composition and organization of tight junctions.

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