Intermediate filaments Flashcards
What makes Intermediate filaments stable?
Helic structure
What is unique to IF
They self assemble and require no nucleation
T/F IF are much more resistant to strain than actin or microtubules
True
What is a structural keratin
Hard apendage (Hair, nail)
how is the nuclear lamin disassembly triggered during mitosis
Phosphorylation by a mitotic kinase
What structural property of an IF allows for assembly to occur by joining two IF proteins to form a dimer kinked through coiled coil?
Alpha helical rod domains give it tensile strength w/o breaking
What two genes are important to IF
Keratin genes and gene Super families.
What species group is keratin only found in
Animals
Where are keratins found in the stratified epithelium?
the suprabasal layers
What two groups are Keratins in IF.
Type I and Type II
Which is the most diverse? IF, Actin filaments or microtubules
Intermediate filaments.
Where are Type I IF found
Skin, bones, tendon, teeth
Where are Type II IF found?
Cartilage and Intravertabrate disks.
Where are type III IF found?
Organs, smooth muscle, muscle
Where are type IV IF found?
Basal lamina of epithelium
Where is desmin found
Muscle
Where is vimentin found?
Connective tissue
How do Keratins form attachments to cell membranes
By binding to hemidesmosomes and Desmosomes
What is unique about Type V IF
They are Lamins found in nucleus and have NLS tails
How many types of Keratins are there in humans?
> 50
Are Keratins co expressed or independent?
Co-expressed
What are properties of Lamins
They are Parallel dimers
Where are Type I and II IF mutually found
Epithelial cells
What is the most Common IF
Keratin
What are the 3 types of Keratin
Simple
Structural
Barries
what are Simple keratins?
Proliferate. (blood vessles and intestines
what are barrier keratin
Stratified epithelium (skin, glands, esophagus)
What are structural Keratin
Hard appendages.
How are Keratin structured in epithelial cells
in Sheet like organization
Why are antibodies to specific IF important for monitoring cell differentiation in pathology
Keratins can signal a spreading tumor if found in the wrong place.
What is the key difference in simple and barrier keratins
Simple keratins only form one layer
What causes Epidermolysis bullosa simplex
Mutations of K5 and K14 leads to cell fragility and when ruptured, fluid accumulation
What catagory does desmin fall in
Type III
Do IF require ATP for growth like other filaments?
No
What type of IF is found in specialized structures like hair and nails?
Keratin
