Cytoskeleton II
Chapter 16
Tubulin heterodimer is the microtubule subunit
Microtubule structure
Growing and shrinking microtubules
Growing and shrinking microtubules
Structure of actin
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 hemidesmosomes
Polymerization of tubulin is nucleated by the γtubulin ring
Electron micrograph of purified γ-tubulin
complexes
Single microtubules nucleated from the γ-tubulin
ring
The centrosome is the major microtubule organizing
center of animal cells and contain γ-tubulin ring
complexes
Centriole surrounded by centrosome matrix
figure 09-08a.jpg
figure 09-08a.jpg
figure 09-09.jpg
Figure 9.9
Figure 9.9
spindle
figure 09-08b.jpg
Leading edge of cell nucleates actin filaments
all actin filaments
Newly formed
actin filaments
Model for actin filament nucleation by ARP
complex
ARP complex nucleates more efficiently when
bound to preexisting actin filament
Electron micrograph of branched actin filaments
Thymosin inhibition
Profilin recruitment
Stathmin sequesters free tubulin
Monomer concentration and capping protein
determine growth or shrinkage rate
Stabilization and destabilization of microtubules
Capping proteins direct microtubules to specific
locations in the cell