Keratin is a type of cytoplasmic intermediate filament found in epithelial cells that makes up hair, skin and nails. There are approximately fifty different types of keratin in the human genome, making it the most diverse type of intermediate filament.They provide mechanical strength to the cell and can connect to filaments in other cells at sites called desmosomes. Each keratin filament comprises of acidic and basic chains which join to form a two heterodimers. These two heterodimers then join to form the tetramer subunit of the larger, stable polymer. A single cell can produce many types of keratin and this forms a single keratin network. Keratin networks that cross-link with each other are held together by disulphide bonds.
- ↑ Molecular Biology of The Cell, 5th Edition, 2008, Alberts et al., Pages 985-986