Cytosquelette 3: Intermediate filaments

Question 1

What is the main funciton of intermediate filaments?

Answer 1

Important for mechanical stress

Allow the cell to endure some pressing and stretching

Question 2

How are these filaments formed?

Answer 2

Monomers that form dimers that form tetramers (where the dimers are on opposite sides)

Then all the tetramers roll together like a rope
page 84

Question 3

What are the 5 types of intermediate filaments and where do we find them? (important)

Answer 3

Keratine:

• Epithelium

Desmine:

• Muscular cells

Neurofilaments :

• Neurons

Vimentine:

• Connective tissue

Nuclear Laminae:

• All nuclei

Question 4

TRUE OR FALSE, intermediate filaments unlike actin and microtubules are not polar.

Answer 4

True

Beacuse intermediate filaments are made of anti-parallel tetramers, they are not polar

Question 5

What kind of filament creates desmosomes?

Answer 5

intermediate filaments

Question 6

What are stereocilia?

Answer 6

Not cilia but rather microvilli that come from actin

Important for hearing

Found in the cochlea

Question 7

What are Interdigitation lateral?

Answer 7

folding of lateral walls to increase contact surface

Question 8

What kind of junction is zona occludens and what are two proteins associated with this?

Answer 8

Tight junction: claudins and occludes

Question 9

What filament is most likely to be bound to cadherens what about desmosomes ?

Answer 9

actine!!! for cadherens

intermediate filaments -> desmosomes

Question 10

How are gap junctions formed?

Answer 10

Formée de connexines
transmembranaires
organisées en
connexon.

Question 11

What is the role of integrins?

Answer 11

To bind the basal laminae to the base of the cell.

Question 12

What are hemi-desmosomes?

Answer 12

Les hémidesmosomes resemblent aux
desmosomes de la lame latérale dans le
fait qu’ils se lient aux filaments
intermédiares du cytosquelette, mais
au lieu de contenir des cadhérines qui
lient 2 cellules ensembles, les
hémidesmosomes contiennent des
intégrines qui se lient à la lame basale

Question 13

TRUE OR FALSE, hemidesmoseomes integrins only bind to filaments
intermédiares

Answer 13

False,

At the focal points that are important trigers for intercellular signaling the integrins are bound to actin.

Question 14

What are the constituents of the basal laminae?

Answer 14

• laminine
• fibronectine
• protéoglycanes
• collagène de type IV
• perlécans