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BMS242 Cell and Molecular > L23 - Cell Motility > Flashcards

L23 - Cell Motility Flashcards

(61 cards)

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1
Q

What is the ECM made up from

A

Many components including firbronectin, laminin, collagen and elastin

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2
Q

Is fibronectin membrane bound?

A

No is a secreted molecules

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3
Q

How many domains does fibronectin contain - what is the function of these

A

Many domains, one domain binds heparin

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4
Q

Describe the structure of laminin

A

Trimer

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5
Q

What does laminin interact with at its Cā€™ terminal end

A

Integrins, dystroglycans, perelecans

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6
Q

Describe what may increase integrin binding to the ECM

A

Intracellular signsls

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7
Q

Integrins forms

A

Heterodimers

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8
Q

Each monomer of the integrin heterodimer contains

A

One single transmembrane domain

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9
Q

What sort of bonds are found in the a subunit of integrin - where do these bonds form

A

Disulphide bonds - cytenine rich doamins

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10
Q

The N terminal of integrins is capable of binding

A

Divalent cations

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11
Q

What are the two itnegrin subints

A

a and B

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12
Q

What does integrin connect to inside of the cell - what mediates this

A

Binds actin filaments which is mediated by tali and vinculin

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13
Q

How many a integrin types

A

18

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14
Q

How many b integrin subtypes

A

8

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15
Q

How many total variatns can the different a and b integrin subunits form

A

24 variants

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16
Q

Describe the structure of inactive integrin

A

EC domain is folded up into its inactive state

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17
Q

When the EC domain of integrin bind s to the ECM describe what happens

A

Induction of confirmational changes which causes activation of the IC domain this is outside in activation

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18
Q

Desribe inside out activation of integrins

A

Activation of the IC domain through IC signalling - interaction with talin causing the activation of the EC domain

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19
Q

What is FAK

A

Focal adhesion kinase

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20
Q

Describe how FAK is activated

A

Intregrin binding to the ECM causes phosphorylation and activation of FAK

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21
Q

Describe the FAK pathway

A

Fibroncectin interacts with integrin - activates FAK - Phosphorylation of tyrosines in that region of focal adhesion - polymerisation of actin fibres

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22
Q

What is Fak involved in

A

The recycling of focal adhesions to enable migration - acts a timer for the adhesion

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23
Q

If certain cell types are not adhered to their substrate describe what happens

A

Cell death follows this is mediated throguh focal adhesion kinases

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24
Q

What is the name of the process of cell death which occurs when attachement to the substrate is lost

A

Anoikis

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25
Mammalian cell motility is mostly based on which molecule
Actin based
26
What are excluded from the region where actin filaments push through
Microtubules and intermediate filaments
27
Ruffling is dependent on what and allows the sensing of
Actin and allows the sensing of guidance cues
28
Myosin II assists in the
Retraction of the tail
29
The lamellipodium extends in direction
Of migration
30
What does the cortex aid
Membrane tension
31
What is added at the leading edge
Actin fibres
32
Tension is transmitted via the
Cortex
33
How is the cell highly polarised during migration
Different things are happening at either of the ends
34
What is the action of cytochalasin B
Lands on + ends of the actin and prevents any further elongation
35
Once actin is capped what begins to be seen
Actin filaments begin to depolymerise
36
What activateds the ARP complex
Rax kinase
37
What is the function of the ARP complex
Nucleation of actin monomrs to form filaments
38
How does ARP2/3 aid in actin nucelation
Both resemble actin so aid nucleation in this way
39
Actin branches from at what angle
70
40
Describe how branch formation aids in the movement of the cell
Branches are forming to push the leading edge forward
41
What happens to actin at the - end? What must then happen to it
Actin depolymerises - must be transported back to the leading edge so that they can be assemble
42
When the rear edge is moving forward - what must happen to interactions
They are broken
43
Focal contacts are
Turned over
44
What have roles in the maturation of focal adhesions
Actin binding proteins, small G-proteins, myosins
45
Low density adhestions are
Very sparse
46
Low density adhesions require
Rac1 and cdc42
47
High density adhesions require
RhoA and actin-myosin interaction
48
Describe the mobility of low density adhesions
Immobile
49
Descirbe the mobility of high density adhesions
Slide in the membrane
50
Example of a soluble molecules as a signal for motility
Netrins
51
How can fibronectin be a signal for migrating cells
Specific forms of fibronecctin can be laid down which other cells are then able to follow
52
Describe the affect of using antibodies to fibronectin
Inhibits migration as interaction with fibronectin is no longer possible
53
Which motif does fibronectin recongise and bind to
Arg Gly, Asp
54
What is the Arg, Gly, Asp motif also known as
RGD
55
What is the effect of injection of an RGD motif
Inhibits migration since fibronectin binding sites are swamped out and binding no longer possible
56
Exocytosis occurs where
At the leading end
57
Where does endocytosis occur
Arround the cell
58
Overall is there a net membrane addition or removal
Addition
59
If membrane is fixed by focal contacts and membrane cycling is occuring what is the effect of this on the cell
Cell is able to move forward
60
What are the roles (4) of endocytosis in motility
Shaping chemotactic gradients: Confining signalling: Modulation of adhesion contacts and ECM: Polarisation of endocytosis
61
How is adhesion removed
Receptor pulled out of the membrane

BMS242 Cell and Molecular (26 decks)

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