Chapter 16

The Cytoskeleton

Cell stained with general protein stain shows the cytoskeleton

Filaments are made of small protein subunits

Single protofilament is easy to break

Multiple protofilaments are more stable

Lateral contacts make a strong filament

Cytoskeleton can reshape rapidly

Tubulin heterodimer is the microtubule subunit

Microtubule structure

Microtubules preferentially grow at the plus end

Dynamic instability of microtubules inside a cell

Rapid cytoskeletal changes in fruit fly embryo

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Growing and shrinking microtubules

Growing and shrinking microtubules

Growing microtubule has GTP containing tubulin subunits at its end

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Structure of actin

Nucleation is the rate limiting step

If actin filaments instead of actin subunits are starting point polymerization starts much faster

Actin binds to many different proteins

Intermediate filaments

Model of intermediate filament structure

Model of intermediate filaments

Intermediate filaments can withstand high levels of deforming force

Keratin filaments in an epithelial cell

Blistering of the skin caused by a mutant keratin gene

Normal skin

Blistering of the skin caused by a mutant keratin gene

Skin with mutated keratin gene

Blistering of the skin caused by a mutant keratin gene

Cells rupture between the nucleus and the hemi-desmosomes

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