Overview Structure stable polymers unlike microtubules and actin → does not undergo dynamic treadmilling must be degraded via the ubiquitin pathway sends to proteasomes intermediate in size between microfilaments (7 nm) and microtubules (25 nm) Function give strength to the cytoskeleton 5 types TypeFilament nameLocationsStainI-IIKeratinEpithelial cellsCytokeratinIIIDesminMuscle (smooth, cardiac, and skeletal)DesminPeripherinPeripheral nerve axons -VimentinFibroblasts and endotheliumVimentinGlial fibrillary acidic protein (GFAP)Astrocytes and Schawnn cellsGFAPIVNeurofilamentsNeuronsNeurofilament (NF)VLaminsNuclear envelope of all cells- Clinical importance alcoholic liver disease ubiquitinated cytokeratin filaments accumulate in hepatocytes eosinophilic inclusions called Mallory bodies Parkinson's disease alpha-synuclein and ubiquitinated neurofilaments accumulate in neurons of substantia nigra eosinophilic inclusions called Lewy bodies