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Occludin: a novel integral membrane protein localizing at tight junctions
1Department of Information Physiology, National Institute for Physiological Sciences, Aichi, Japan.
The Journal of Cell Biology
|December 1, 1993
Summary
Researchers identified a novel integral membrane protein, occludin, localized exclusively at tight junctions in epithelial and endothelial cells. This discovery advances understanding of cell adhesion and barrier function.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Tight junctions are crucial for epithelial and endothelial cell barrier function.
- ZO-1 is a known tight junction-associated protein.
- Previous research indicated a distinct protein fraction at adherens junctions.
Purpose of the Study:
- To identify and characterize a novel integral membrane protein localized at tight junctions.
- To elucidate the structure and function of this newly discovered protein.
Main Methods:
- Generation of monoclonal antibodies against a chick liver protein fraction.
- Immunofluorescence and immunoelectron microscopy for protein localization.
- cDNA cloning and sequencing to determine protein structure.
Main Results:
- A novel approximately 65-kD integral membrane protein was identified.
- This protein, designated occludin, was exclusively localized at tight junctions.
- cDNA sequencing revealed a 504-amino acid polypeptide with no significant homology to known proteins.
- Hydrophilicity analysis suggested four membrane-spanning segments, similar to connexins.
Conclusions:
- Occludin is a novel integral membrane protein found at tight junctions.
- Its structure suggests a role in forming the tight junction seal.
- This finding provides a molecular basis for understanding tight junction structure and function.