Biomaterial Database

Identification of a 160-kDa polypeptide that binds to the tight junction protein ZO-1. 1991

B Gumbiner, and T Lowenkopf, and D Apatira

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

ZO-1 is a 210- to 220-kDa peripheral membrane protein associated with the cytoplasmic surface of the epithelial tight junction. Because ZO-1 may interact with other unidentified tight junction proteins, we have looked for other polypeptides that bind to ZO-1. A 160-kDa polypeptide was identified that coimmunoprecipitates with ZO-1 from detergent extracts of metabolically labeled Madin-Darby canine kidney (MDCK) cells. This polypeptide appears to be distinct from ZO-1, rather than a degradation product, by several criteria. It lacks ZO-1 epitopes recognized by both monoclonal antibodies and a polyclonal serum to ZO-1, since it is not detectable in immunoblots of either whole cell extracts or ZO-1 immunoprecipitates. Also, it exhibits a peptide map different from that of ZO-1 on one-dimensional "Cleveland gels." Moreover, because the kinetics of appearance of newly synthesized 160-kDa polypeptide in anti-ZO-1 immunoprecipitates is much slower than that of ZO-1, its presence in immunoprecipitates cannot be simply explained by degradation of ZO-1 during cell lysis. Like ZO-1, the 160-kDa polypeptide seems to be a cytoplasmic peripheral membrane protein. It cannot be labeled by two different cell surface labeling reagents. It can be extracted from the membrane by high salt concentration in the absence of detergents. As expected for a protein complex, the 160-kDa polypeptide and ZO-1 turn over with similar kinetics. We propose that the 160-kDa polypeptide is a component of the tight junction.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010449	Peptide Mapping	Analysis of PEPTIDES that are generated from the digestion or fragmentation of a protein or mixture of PROTEINS, by ELECTROPHORESIS; CHROMATOGRAPHY; or MASS SPECTROMETRY. The resulting peptide fingerprints are analyzed for a variety of purposes including the identification of the proteins in a sample, GENETIC POLYMORPHISMS, patterns of gene expression, and patterns diagnostic for diseases.	Fingerprints, Peptide,Peptide Fingerprinting,Protein Fingerprinting,Fingerprints, Protein,Fingerprint, Peptide,Fingerprint, Protein,Fingerprinting, Peptide,Fingerprinting, Protein,Mapping, Peptide,Peptide Fingerprint,Peptide Fingerprints,Protein Fingerprint,Protein Fingerprints
D010750	Phosphoproteins		Phosphoprotein
D011233	Precipitin Tests	Serologic tests in which a positive reaction manifested by visible CHEMICAL PRECIPITATION occurs when a soluble ANTIGEN reacts with its precipitins, i.e., ANTIBODIES that can form a precipitate.	Precipitin Test,Test, Precipitin,Tests, Precipitin
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations