Tonofibril
Protein cytoskeletal component
From Wikipedia, the free encyclopedia
Tonofibrils are cytoplasmic protein structures in epithelial tissues that converge at desmosomes and hemidesmosomes.[1] They consist of bundles of keratin intermediate filaments (tonofilaments) in epithelial cells that are anchored to the cytoskeleton.[2][3] They were discovered by Rudolf Heidenhain, and first described in detail by Louis-Antoine Ranvier in 1897.[4]
Composition
Tonofilaments are keratin intermediate filaments that make up tonofibrils in the epithelial tissue. They may also just be referred to as keratin intermediate filaments.[5] In epithelial cells, tonofilaments loop through desmosomes. Electron microscopy has advanced now to illustrate the tonofilaments more clearly.[1]
The protein filaggrin is believed to be synthesized as a giant precursor protein, profilaggrin (>400 kDA in humans). When filaggrin binds to keratin intermediate filaments, the keratin aggregates into macrofibrils.[3]
