MCB Lecture 37 Junctions Flashcards Preview

Miscellaneous > MCB Lecture 37 Junctions > Flashcards

Flashcards in MCB Lecture 37 Junctions Deck (29)
0

What is the function of Desmosomes?

Desmosomes connect two cells together.
Distribution of tensile forces

1

Where are Desmosomes localised? What do they connect?

They are localised in the apical region
They connect two cells

2

Describe the proteins involved in Desmosomes

Cadherin family proteins
Adaptor proteins: desmoplakin, plakoglobin
Intermediate filaments

3

What is the function of cadherin?

It forms the interaction between the two cells in a Desmosome

4

Which cytoskeletal element to Desmosomes connect to?

Intermediate filaments

5

What are two problems that can occur with Desmosomes ?

1. Mutation in the intermediate filament (keratin)
2. Antibodies for the Desmosome interrupt it

6

What are focal adhesions? What is their function?

They are attachments between the cell and the extracellular matrix
They are involved with cell locomotion and signalling

7

Describe the protein involved with focal adhesions

Integrins attach cell to the ECM
Adaptor proteins: vinculin, Tallin
Actin filaments

8

Which cytoskeletal element is involved with focal adhesions?

Actin filaments

9

What is an integrin?
Describe its structure
How is there variability in integrin structure?
Which junctions have integrin?

It is a protein that connects cells together
It is made up of an alpha and beta subunit
Variability: different alpha and beta subunits present
Focal adhesions and hemidesmosomes have integrins

10

Describe how cells move

1. Protrusion
2. Adhesion
3. Traction

11

What forces are produced by focal adhesions

Cell traction forces
CTF

12

Describe how focal adhesions are involved in cell signalling.
What are the two types?

1. Inside out:
Ligand binds to a receptor (GPCR, tyrosine kinase) on the cell membrane. This starts a signal transduction pathway, leading to the activation of talin. Talin binds, and now extracellular matrix proteins can be engaged

2. Outside in:
Binding of an ECM protein to the integrin initiates a signal transduction pathway
Kinases (FAK) recruited
Gene expression, cell proliferation etc.

13

Describe inside-out signalling with focal adhesions

Ligand binds to a receptor (GPCR, tyrosine kinase) on the cell membrane. This starts a signal transduction pathway, leading to the activation of talin. Talin binds, and now extracellular matrix proteins can be engaged

14

Describe outside -in signalling in focal adhesions

Binding of an ECM protein to the integrin initiates a signal transduction pathway
Kinases (FAK) recruited
Gene expression, cell proliferation etc.

15

What is FAK?

It is Focal adhesion Kinase
It is activated when ECM proteins bind to integrins in focal adhesions

It initiates a cascade of transduction events

16

What is the function and location of hemi desmosomes?

These connect cells to the ECM
They give high tensile strength (eg in skin)

17

What proteins are involved in hemi desmosomes?

Integrins
Adaptor proteins
Intermediate filaments

18

Which cytoskeletal element is involved with hemi desmosomes?

Intermediate filaments

19

How are hemi desmosomes involved with cell proliferation?

When tension is detected by the integrins, a transduction pathway is initiated, leading to cell proliferation and G1 progression

20

What do mutations in integrins cause?

Skin blistering

21

What are the anchoring cell junctions?

Desmosomes
Adherens
Hemi desmosomes
Focal adhesions

22

Describe the function of Gap junctions

They allow for direct movement of materials from one cell to another through a small channel

23

Describe the structure of gap junctions

6 connexons form a connexon
Two connexons (one on each cell) line up to form a channel

24

How much space is there between two cells linked by a gap junction?

2-4 nm

25

What is meant by homo and heteromeric connexons?

Homo: only one type of connexin present
Hetero: different types of connexin

26

What is meant by homo and heterotypic channels in gap junctions?

Homo: only one type of connexin
Hetero: different types of connexin in the channel

27

What are the functions of gap junctions? (3)

1. Movement of metabolites
2. Movement of ions in synapses
3. Electrical signalling

28

What causes congenital deafness?

Defects in gap junction connexins

Decks in Miscellaneous Class (109):