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Making a connection: direct binding between keratin intermediate filaments and desmosomal proteins
P D Kouklis1, E Hutton, E Fuchs
1Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637.
The Journal of Cell Biology
|November 1, 1994
Summary
Desmoplakin (DPI) directly binds to the head of type II epidermal keratins, explaining the stable keratin filament structure in skin cells. This interaction is crucial for understanding blistering skin disorders.
Area of Science:
- Cell Biology
- Biochemistry
- Dermatology
Background:
- Keratin intermediate filaments connect to desmosomes in epidermal cells, forming cytoskeletal structures.
- Desmoplakin (DPI) is implicated in this keratin-desmosome interaction, but direct evidence is lacking.
Purpose of the Study:
- To investigate the biochemical basis of keratin filament and desmosome connections in epidermal keratinocytes.
- To demonstrate direct interactions between desmoplakin and keratin filaments.
Main Methods:
- Engineered and purified recombinant K5 head and DPI tail.
- Utilized solution-binding and ligand blot assays to demonstrate in vitro interactions.
Main Results:
- The carboxy-terminal tail of DPI directly associates with the amino-terminal head of type II epidermal keratins (K1, K2, K5, K6).
- This specific association was not observed with simple epithelial type II keratins, vimentin, or type I keratins.
- An 18-amino acid region in the K5 head, conserved in epidermal keratins, is involved in DPI tail binding.
Conclusions:
- Direct binding between DPI and type II epidermal keratins stabilizes the keratin filament architecture in skin.
- This interaction mechanism may be relevant to blistering skin disorders caused by mutations in this binding site.