Intermediate Filaments Function

The definition of intermediate filaments is that they are a part of the cytoskeleton. The cytoskeleton is a protein filament-based internal structure of the cell. The cytoskeleton has a variety of functions in the cell, including providing structure and support as well as serving as a network for intracellular transport. Cell motility and cell division are also highly influenced by the cytoskeleton. The cytoskeleton is made up of three primary filaments:

• Microtubules
• Intermediate filaments
• Microfilaments

• Microtubules:-Microtubules are the cytoskeleton’s biggest filaments and are involved in cell structure, cell division, and intracellular trafficking.

• Microfilaments:-Microfilaments are the cytoskeleton’s smallest filaments, and they’re vital for cell motility, plasma membrane anchoring, and contractility.

• Intermediate Filaments:-The cytoskeleton is made up of intermediate filaments, which are medium-sized protein filaments. They provide structure and support and, in comparison to microtubules and microfilaments, tend to create more lasting structures. As a result, they constitute an essential component of the cytoskeletal system, bearing the brunt of the cell’s strain.

Intermediate Filaments Function

Intermediate filaments’ major job is to give cells support and structure. Intermediate filaments are a permanent element of the cytoskeleton that aid in the cell’s structure. They also play a role in cell cohesion and extracellular matrix attachment. This enables epithelial cells, which make up the outer layers of our skin and organs, to form tight barriers and remain cohesive even while under tension. Keratin is produced in huge quantities by epithelial cells of the skin, which helps to hold them together and resist mechanical stress.

Blistering disorders of the skin can result from mutations in intermediate proteins, in which the skin is not properly adhered to the basement membrane. Epidermolysis bullosa simplex (EBS), for example, is a disorder caused by mutations in keratin proteins that prevent them from effectively polymerizing. Even minor abrasions cause skin blistering as a result of this. Other illnesses have been linked to intermediate filaments. Motor neurons, for example, degenerate over time in amyotrophic lateral sclerosis (ALS), and patients lose control of their motor activities. Patients lose muscle mass, atrophy, and die as a result of paralysis over time. ALS, often known as Lou Gehrig’s disease, is characterised by an abnormal accumulation of intermediate filament proteins known as neurofilaments.

Intermediate Filaments Structure

Intermediate filaments are a category of proteins with a wide range of functions. They’re made up of a variety of proteins, including:

• Keratin
• Desmin
• Lamin
• Vimentin
• Neurofilaments

Intermediate filaments are made up of nearly fifty distinct proteins. Despite their differences in structure and function, all intermediate filaments have some characteristics. A core alpha-helical rod domain makes up intermediate filaments. 1A, 1B, 2A, and 2B are the four alpha-helical segments that make up the domain. Three linker regions separate each segment. The central building component of an intermediate filament is a coiled-coil structure, which is made up of two interwoven proteins. Intermediate filaments have an average diameter of 10 nm.

Intermediate filaments are twisted protein strands in the shape of a helix. The proteins’ separate subunits form dimers, which then join to form tetramers. As protofilaments, the tetramers assemble end to end.

Lamins

Lamins were most likely the earliest intermediate filaments created during evolution. Because they live in the nucleus close beneath the nuclear envelope, they have a very long rod domain and convey a nuclear transport signal. Except for a gap at the nuclear pore complex locations, they are continuous.

They form a lattice-like array in the image above (from Alberts et al, Garland Press, NY). An electron micrograph of the area containing the lamins, just inside the nuclear envelope, can be seen in the picture to the left. They’re hard to tell apart from the thick heterochromatin in the vicinity.

Based on amino acid sequence and protein structure similarities, there are six types of intermediate filaments:

• Type I – acidic keratins
• Type II – basic keratins

Note that type I and type II intermediate filaments bond together to produce acidic-basic heterodimers, which then join to form a keratin filament.

Desmin (sarcomere structural components), glial fibrillary acidic protein (GFAP, in astrocytes and certain glial cells), peripherin (in peripheral neurons), and vimentin (in peripheral neurons) are all members of Type III (in fibroblasts, leukocytes, endothelial cells)

• Alpha-internexin, neurofilament proteins (in neuronal processes), synemin, and syncoilin are all examples of type IV proteins.
• Nuclear lamins belong to Type V.
• Nestin is part of Type VI.

Features

Intermediate filaments are cytoskeletons with a diameter that is halfway between the other two types. It has a diameter of about 10 nm (or ranges from 8 to 12 nm), which is smaller than microfilaments (which have a diameter of about 7 nm) and larger than microtubules (i.e. 25 nm). Two antiparallel helices or dimers of several protein subunits make up an intermediate filament. It can be made up of a variety of proteins and forms a ring around the nucleus of the cell. Stretchable intermediate filaments can be multiplied several times their original length. The intermediate filaments are cytoplasmic, with the exception of nuclear lamin.

The intermediate filaments do not have polarity, unlike microfilaments and microtubules. They don’t have a minus (-) or a plus (+) end, which means they don’t have a minus (-) and a plus (+) end. A binding site for a nucleoside triphosphate does not exist in the intermediate filaments.

Conclusion

Introduction The definition of intermediate filaments is that they are a part of the cytoskeleton. The cytoskeleton has a variety of functions in the cell, including providing structure and support as well as serving as a network for intracellular transport. The cytoskeleton is made up of three primary filaments: Microtubules Intermediate filaments Microfilaments Microtubules:-Microtubules are the cytoskeleton’s biggest filaments and are involved in cell structure, cell division, and intracellular trafficking. Intermediate Filaments:-The cytoskeleton is made up of intermediate filaments, which are medium-sized protein filaments. Intermediate filaments are a permanent element of the cytoskeleton that aid in the cell’s structure. Blistering disorders of the skin can result from mutations in intermediate proteins, in which the skin is not properly adhered to the basement membrane. Intermediate Filaments Structure Intermediate filaments are a category of proteins with a wide range of functions.