IMS 1 TBL 3 Chunk 2 Intermediate Filaments

What is the key structural material in intermediate filaments?

α-keratin

What percentage of cysteine residues are found in keratins?

About 14%

What is the significance of disulphide bonds in keratin?

They provide strength to the filaments.

What happens to cells filled with keratin bundles?

The cells die, and the 'hair' or 'nail' remains.

What are the two types of keratin found in epithelial cells?

Type I: Acidic keratin; Type II: Basic keratin.

What types of cells contain vimentin?

Fibroblasts, endothelial cells, and leukocytes.

What is the role of desmin in muscle cells?

It helps maintain sarcomere alignment by joining myofibrils.

What are neurofilaments primarily found in?

Axonal cells.

What is the function of lamins in cells?

They provide support inside the inner nuclear membrane.

What is the diameter range of intermediate filaments?

8-12 nm.

What is a characteristic of intermediate filaments compared to other filaments?

They are insoluble, stable, and durable.

What diseases are associated with mutations in desmin?

Desminopathies, leading to progressive limb muscle weakness and cardiomyopathy.

What condition is caused by mutations in the KRT5 and KRT14 genes?

Epidermolysis bullosa simplex, which results in blistering skin.

How are intermediate filaments assembled?

By parallel assembly of monomers into dimers, forming staggered antiparallel tetramers.

What is the significance of the polymerisation of intermediate filaments?

It is highly regulated and can be dissociated by urea.

What is the role of intermediate filaments in cells that withstand mechanical stress?

They provide structural support and stability.

What is the process by which intermediate filaments can be modified?

They can be phosphorylated.

What type of junctions involve filamentous proteins like desmin?

Desmosomes.

What is the role of cysteine residues in keratin?

They allow the formation of disulphide bonds between protein bundles.

What is the significance of the lack of polarity in intermediate filament assembly?

Each end of the tetramers is equivalent, allowing for uniform elongation.