Cytoskeleton in most eukaryotic cells consists of three distinct, yet interconnected,
filament systems: Actin filaments,
Microtubules and intermediate filaments. Cell assembly is
integrated by the network of intermediate filaments (IFs) and by their interactions with
other cytoskeleton structural elements defining cytoarchitecture and cytodynamics.
IF network is critically involved in cell shape control and imparts intracellular
mechanical strength. The family of IF proteins has five sub-families. Four of the
sub-families are localized in the cytoplasm, whereas the fifth sub-family is found in the
nucleus. Expression patterns of cytoplasmic IFs are cell- and tissue-type specific.
The main IF protein is found in epithelial cells is
Keratin and in fibroblasts it is
Vimentin. Keratin IFs are
obligate co-polymers of acidic and basic cytokeratins , .
IF networks are cross-linked by special binding proteins, e.g.,
Trichoplein and Plakophilins
, , , .
These proteins maintain cell and tissue integrity by coordinated interconnection of three
distinct cytoskeletal filament systems, and anchoring them to membrane complexes.
Assembly, disassembly and subcellular organization of IFs is regulated by kinases,
e.g., by Mitogen-activated protein kinases 8-10
(JNK(MAPK8-10)) and Cell division cycle 2
(CDK1) , .
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Molecular architecture of intermediate filaments.
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