Intermediate filaments
These are a group of proteins that form the cytoskeleton of cells. They form cytoplasmic filaments of 8 to 10 nm in diameter. There is a conserved central "rod" domain of 310 amino acid residues. This is flanked by "head" and "tail" domains which define the specific intermediate filament and confer immunogenicity. The sequence homology between intermediate filaments confers the potential for cross reaction with monoclonal antibodies. In addition, although these filaments are expressed preferentially by various cell lineages, co-expression is common in tumours.
Intermediate filaments are currently classified into six types:
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Acidic cytokeratin |
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Basic cytokeratin |
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Vimentin, Desmin, Glial fibrillary acidic protein, Peripherin |
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Nuclear laminin proteins |
The initial understanding was that the role of intermediate filaments is structural, forming the cytoskeleton of cells. However, they are now known to bind nucleic acids, to be processed by calcium-activated proteases and by cyclic adenosine monophosphate-dependent protein kinases. The current opinion is that they mediate the interaction the cell with the extracellular environment.
This page last revised 14.12.2001.