Identification of trichoplein, a novel keratin filament-binding protein.
Keratins 8 and 18 (K8/18) are major components of the intermediate filaments (IFs) of simple epithelia. We report here the identification of a novel protein termed trichoplein. This protein shows a low degree of sequence similarity to trichohyalin, plectin and myosin heavy chain, and is a K8/18-binding protein. Among interactions ... between trichoplein and various IF proteins that we tested using two-hybrid methods, trichoplein interacted significantly with K16 and K18, and to some extent with K5, K6a, K8 and K14. In in vitro co-sedimentation assays, trichoplein directly binds to K8/18, but not with vimentin, desmin, actin filaments or microtubules. An antibody raised against trichoplein specifically recognized a polypeptide with a relative molecular mass of 61 kDa in cell lysates. Trichoplein was immunoprecipitated using this antibody in a complex with K8/18 and immunostaining revealed that trichoplein colocalized with K8/18 filaments in HeLa cells. In polarized Caco-2 cells, trichoplein colocalized not only with K8/18 filaments in the apical region but also with desmoplakin, a constituent of desmosomes. In the absorptive cells of the small intestine, trichoplein colocalized with K8/18 filaments at the apical cortical region, and was also concentrated at desmosomes. Taken together, these results suggest that trichoplein is a keratin-binding protein that may be involved in the organization of the apical network of keratin filaments and desmosomes in simple epithelial cells.
Mesh Terms:
Amino Acid Sequence, Animals, Caco-2 Cells, Carrier Proteins, Cell Line, Tumor, Cloning, Molecular, Cytoskeletal Proteins, DNA, Complementary, Desmoplakins, Desmosomes, Green Fluorescent Proteins, HeLa Cells, Humans, Immunoprecipitation, Intermediate Filament Proteins, Intermediate Filaments, Keratin-18, Keratin-8, Keratins, Mice, Microscopy, Electron, Microscopy, Fluorescence, Microtubules, Molecular Sequence Data, Myosin Heavy Chains, Peptides, Plectin, Polymerase Chain Reaction, Protein Binding, Protein Precursors, Protein Structure, Tertiary, Recombinant Proteins, Transfection, Tubulin, Two-Hybrid System Techniques
Amino Acid Sequence, Animals, Caco-2 Cells, Carrier Proteins, Cell Line, Tumor, Cloning, Molecular, Cytoskeletal Proteins, DNA, Complementary, Desmoplakins, Desmosomes, Green Fluorescent Proteins, HeLa Cells, Humans, Immunoprecipitation, Intermediate Filament Proteins, Intermediate Filaments, Keratin-18, Keratin-8, Keratins, Mice, Microscopy, Electron, Microscopy, Fluorescence, Microtubules, Molecular Sequence Data, Myosin Heavy Chains, Peptides, Plectin, Polymerase Chain Reaction, Protein Binding, Protein Precursors, Protein Structure, Tertiary, Recombinant Proteins, Transfection, Tubulin, Two-Hybrid System Techniques
J. Cell. Sci.
Date: Mar. 01, 2005
PubMed ID: 15731013
View in: Pubmed Google Scholar
Download Curated Data For This Publication
215464
Switch View:
- Interactions 16