Filaments

Intermediate filaments (IFs) are one of the primary cytoskeletal systems found in nearly all vertebrate cells. Intermediate filaments are made up of different members of the cytoskeleton Intermediate filaments protein family depending on the cell type. Intermediate filaments proteins are also found in the nucleus, where they serve as the nucleoskeleton’s main structural component.

We present a historical overview of the discovery and characterization of cytoplasmic and nuclear Intermediate filaments in this Review. Furthermore, we investigate many of the properties of cytoplasmic Intermediate filaments that underpin their disease relevance, such as their dynamic properties and participation in cytoskeletal crosstalk, as well as their roles in signalling, mechanical stabilisation, and motility. 

Although Intermediate filaments have been studied in a variety of species, including squid, Xenopus laevis, and Caenorhabditis elegans, this paper focuses primarily on data from mammalian studies.

Intermediate Filaments

Intermediate filaments are named after their thickness, which is greater than that of actin filaments but less than that of microtubules or muscle myosin filaments. Intermediate filament subunits are elongated, not globular, and are associated in an antipolar manner. As a result, there is no polarity in the overall filament, and no motor proteins move along intermediate filaments. Only complex multicellular organisms have intermediate filaments. They are encoded by a diverse set of genes and can be classified into families based on their amino acid sequences. 

Cells in various tissues of the body express one or more of these genes at various times. Over the course of a cell’s life, it can even change the type of intermediate filament protein that is expressed.Most likely, the various forms of intermediate filaments have subtle but critical differences in their functional characteristics, which aid in defining the cell’s function. Intermediate filaments, in general, act as structural elements, assisting cells in maintaining their shape and integrity. 

Keratin filaments, for example, the intermediate filaments of epithelial cells that line body surfaces, provide strength to the cell sheet that covers the surface. When the epithelial cell sheet is weak and prone to rupture, keratin gene mutations can cause blisters. Keratin mutations can also result in hair, nail, and corneal deformations. The lamin family, which includes the nuclear lamina, a fibrous shell that underpins and supports the nuclear membrane, is another example of an intermediate filament family.

Filament yarn

Filament yarn is composed of one or more continuous strands known as filaments, each of which runs the entire length of the yarn. Monofilament yarns are those made up of only one filament, while multifilament yarns contain multiple filaments. A multifilament yarn for apparel applications can have as few as 2 or 3 filaments or as many as 50.

A filament yarn in carpeting, for example, could be made up of hundreds of filaments. The majority of synthetic fibres are in the form of filament yarn. Silk is the only significant natural filament yarn.

Filament yarns are classified into two types based on the shape of the filaments: flat and bulk.A flat yarn’s filaments are straight and neat, parallel to the yarn axis. As a result, flat filament yarns are typically tightly packed and have a smooth surface. Bulked yarns have a higher volume than flat yarns of the same linear density because the filaments are either crimped or entangled with each other.

Texturing is the primary method for creating bulked filament yarns. Textured yarn is created by incorporating long-lasting crimps, coils, and loops along the length of the filaments. Because textured yarns have a higher volume than flat yarns, the air and vapour permeability of fabrics made from them is higher. 

However, for applications requiring low air permeability, such as fabrics for air conditioning.

Actin filaments

These, also known as microfilaments, are the smallest filaments (in diameter) in the cell, measuring approximately 7nm in diameter. They are composed of actin monomers that polymerize into filaments with two strands that wrap around each other.

Actin filaments play an important role in cell shape and motility. Approximately half of the actin in a cell is unpolymerised. This actin pool can be rapidly released to polymerize new actin filaments and push out new projections from the cell. Actin filaments can rapidly polymerise and depolymerised in response to cellular signals, causing the cell shape to change.

Actin filaments also serve as a pathway for myosin motors, which can transport vesicles or interact with actin filaments to contract the cell, as in muscle.

Tight junctions are associated with actin. Because of its ability to interact with myosin, it can form a contractile network within the cell with actin. This contractile network is less organised than the actin and myosin filament network found in skeletal muscle.

Conclusion

Filaments are named after their thickness, which is greater than that of actin filaments but less than that of microtubules or muscle myosin filaments. Intermediate filaments are made up of different members of the cytoskeleton Intermediate filaments protein family depending on the cell type. Over the course of a cell’s life, it can even change the type of intermediate filament protein that is expressed. Keratin filaments, for example, the intermediate filaments of epithelial cells that line body surfaces, provide strength to the cell sheet that covers the surface. Filament yarn is composed of one or more continuous strands known as filaments, each of which runs the entire length of the yarn. The majority of synthetic fibres are in the form of filament yarn. Filament yarns are classified into two types based on the shape of the filaments: flat and bulk.