Cytoskeleton - 28 - Intermediate Filaments

What are intermediate filaments

Part of the cytoskeleton that provides tensile strength and distributes mechanical stress through connected cells via desmosomes (flexibilty)

What are intermediate filaments made of?

fibrous subunits containing a central ⍺-helical rod domain two unstructured domains. Rod domains pair to form stable coiled dimers and then two dimers associate to form a tetramer which are then formed into a helical array to containing 8 tetramers

Do intermediate filaments have polarity?

No

What are the classes of Intermediate filaments?

Cytoplasmic and Nuclear

What are the types of Cytoplasmic intermediate filaments?

Keratin, Vimentin and vimentin-related filaments and neurofilaments

What are the type(s) of nuclear intermediate filaments?

Nuclear lamins

Where are keratin filaments found?

Epithelial cells. Also specialized keratins occur in hair, feathers, and claws.

How do they connect epithelial cells?

Indirectly through desmosomes

Where are neurofilaments found?

Along axons of vertebrate neurons providing strength and stability

Explain neurofilaments role in ALS

Abnormal accumulation of neurofilaments in the cell bodies and axons of motor neurons, resulting in axon degeneration and muscle weakness

Where are nuclear lamins found?

On the inner nuclear membrane

What functions do the nuclear lamins perform

Helps properly position chromosomes. Also disassembles and reassembles during each cell division

What are consequences of faulty nuclear lamina?

Progeria, increased cell death and improper tissue repair

What is plectin and it’s function?

It’s a protein that cross-links intermediate filaments into bundles and connects them to microtubules, actin filaments and desmosomes, which provides mechanical support.