Intermediate Filaments
Intermediate Filaments - Related Videos
00:57
Formation of Intermediate Filaments
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2023
Intermediate filaments are cytoskeletal proteins with higher tensile strength and flexibility than microfilaments and microtubules. Unlike the other two cytoskeletal proteins, intermediate filament formation lacks the enzymatic activity to hydrolyze nucleotides like ATP and GTP to generate energy for polymerization. Therefore, the formation of intermediate filaments is multistep self-assembly. The involvement of any accessory proteins in intermediate filament formation has not yet been reported.
01:35
Disassembly of Intermediate Filaments
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2023
Intermediate filaments (IFs) do not undergo spontaneous disassembly. Enzymes, kinases, and phosphatases add and remove phosphates from specific sites to regulate their disassembly. The IF concentration in the cytoplasm also regulates the disassembly. If the concentration crosses a threshold, it activates the protein kinases in the vicinity, allowing the phosphorylation of IFs. Keratin proteins, found at the cell periphery near cell junctions, undergo a cycle of assembly and disassembly. In Type...
01:31
Types of Intermediate Filaments
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2023
The intermediate filaments are an essential component of the cytoskeleton. Presently six types of intermediate filament have been identified. Type I and II are acidic and basic keratin proteins. Type III is of mesodermal origin and comprises four proteins: vimentin, desmin, glial fibrillary acidic protein (GFAP), and peripherin. Vimentin is commonly found in mesenchymal cells, desmin in muscle cells, GFAP in astrocytes, while peripherin is found in peripheral nervous system neurons (PNS). Type...
01:19
The Structure of Intermediate Filaments
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2023
The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of microfilaments (7 nm) and the microtubules (25 nm). These filaments are highly stable and can remain intact when exposed to high salt concentrations and detergents. These filaments are responsible for providing stability and mechanical support to the cells. They also help in cell adhesion and maintaining tissue integrity. Intermediate filaments...
09:29
Isolation of Intermediate Filament Proteins from Multiple Mouse Tissues to Study Aging-associated Post-translational Modifications
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Cited by 5 •
2017
In this method, we present biochemical procedures for rapid and efficient isolation of intermediate filament (IF) proteins from multiple mouse tissues. Isolated IFs can be used to study changes in post-translational modifications by mass spectrometry and other biochemical assays.
FAQs
Assembly begins when protein subunits form coiled-coil dimers, which align in an antiparallel arrangement to create tetramers. These tetramers then associate progressively into thicker, flexible fibers approximately 10 nanometers in diameter. This stepwise organization produces durable cellular structures capable of distributing mechanical forces while preserving the overall architecture of the cell.
Because intermediate filaments lack intrinsic polarity, their two ends are structurally equivalent, unlike the directionally organized ends of actin filaments and microtubules. They are also relatively stable rather than rapidly reorganized. Together, these properties support persistent reinforcement and shape maintenance, allowing cells to tolerate mechanical stress without relying on constant filament remodeling.
These proteins provide cell- and structure-specific reinforcement. Keratins support tissues, vimentin contributes to cellular organization, desmin supports tissue architecture, neurofilaments help maintain neuronal structures, and nuclear lamins reinforce the nucleus. Their distinct distributions allow intermediate filament systems to match the mechanical and organizational demands of particular cell types and compartments.
Intermediate filaments contribute durability and mechanical resilience, whereas actin filaments and microtubules represent cytoskeletal systems with different structural properties. Their relative stability and lack of polarity make intermediate filaments especially suited to maintaining cell shape and integrity. Considering all three systems together gives a more complete view of how cells organize internal structures and withstand stress.
Examining which intermediate filament proteins are present and how their fibers are organized can clarify how cells establish architecture during tissue development and respond during wound repair. Because these proteins support tissue structure and cellular organization, changes in their arrangement may reveal how mechanical stability and coordinated tissue rebuilding are maintained.
Intermediate filament research helps connect altered protein composition or filament organization with disease-related loss of cellular integrity. Mutations or disrupted organization can affect the structures that support cells, tissues, organelles, or the nucleus. Studying these changes provides a framework for understanding how defects in cytoskeletal architecture contribute to biological dysfunction.