Identification and characterization of a novel mammalian intermediate filament-associated protein.
A novel monoclonal antibody, designated M1.4, recognizes the high molecular weight microtubule-associated protein MAP1A (ca. Mr 380 kD) in both bovine and rat brain. In HeLa cells, however, M1.4 binds to a 240 kD polypeptide on immunoblots and co-localizes with both vimentin and cytokeratin filaments using double-label immunofluorescence microscopy. Immunoelectron microscopy indicates that the 240 kD polypeptide localizes along bundled intermediate filaments in a periodic manner. Two-dimensional electrophoretic analysis indicates that the 240 kD polypeptide has a basic pI of 7.7. When HeLa cell intermediate filaments are isolated using standard non-ionic detergent/high-salt conditions the 240 kD polypeptide does not sediment with the intermediate filaments, unlike the established intermediate filament-associated protein plectin. Immunoblot analysis with M1.4 shows the 240 kD polypeptide is expressed in a number of mammalian cell lines. Additionally, double-label immunofluorescence shows the 240 kD polypeptide to associate with vimentin filaments in African Green Monkey kidney (CV-1) and JC neuroblastoma cells. Due to its unique biochemical and biological characteristics, the 240 kD polypeptide is clearly a novel intermediate filament-associated protein for which we have proposed the designation gyronemin (Gr. gyros: around; nemin: filament).
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Department of Cell Biology and Anatomy, School of Medicine and Dentistry, University of Alabama, Birmingham 35294.
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D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000302:isolation & purification*; D008869:Microtubule-Associated Proteins / Q000276:immunology; D008970:Molecular Weight; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity
D000911:Antibodies, Monoclonal; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins