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JACOP, a novel plaque protein localizing at the apical junctional complex with sequence similarity to cingulin

Hiroe Ohnishi1, Takuo Nakahara, Kyoko Furuse

  • 1Department of Cell Biology, Kyoto University Faculty of Medicine, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan.

The Journal of Biological Chemistry
|August 5, 2004
PubMed

Insights

Researchers identified JACOP, a novel junction-associated coiled-coil protein, crucial for linking the apical junctional complex, particularly tight junctions, to the cell's actin cytoskeleton in epithelial and endothelial cells.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The apical junctional complex regulates cell barrier function.
  • It comprises cell adhesion molecules and cytoplasmic plaque proteins.
  • Understanding these components is key to tissue integrity.

Purpose of the Study:

  • To clone and characterize a novel protein (p155) found at the apical junctional complex.
  • To investigate the function and localization of this protein in various cell types.
  • To elucidate its role in anchoring the junctional complex to the cytoskeleton.

Main Methods:

  • Monoclonal antibody screening to identify a chicken p155 homolog.
  • cDNA cloning and sequencing of the mouse homolog.
  • Immunofluorescence and immunoelectron microscopy for protein localization.
  • Overexpression studies in epithelial cells and fibroblasts.

Main Results:

  • A mouse homolog of p155, named JACOP (junction-associated coiled-coil protein), was cloned.
  • JACOP, a 148-kDa protein with a coiled-coil domain, localizes to the junctional complex in epithelial and endothelial cells.
  • JACOP associates with tight junctions and adherens junctions, and also with non-junctional actin filaments.
  • Overexpression confirmed JACOP's recruitment to junctional complexes and stress fibers.

Conclusions:

  • JACOP is a novel component of the apical junctional complex.
  • It plays a role in connecting the junctional complex, especially tight junctions, to the actin cytoskeleton.
  • JACOP is essential for maintaining cell structure and tissue integrity.

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