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SL12002 Cell Biology > Cell signalling 3 > Flashcards

Cell signalling 3 Flashcards

1
Q

What does Raf use to phosphorylate and activate Mek?

A

ATP

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2
Q

What does activated Mek do?

A

It phosphorylates and activated Erk

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3
Q

What does Mek use to phosphorylate and activate Erk?

A

ATP

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4
Q

What can activated Erk do?

A

Phosphorylate, and thus activate different proteins and transcription factors

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5
Q

What can the proteins and transcription factors activated by Erk do?

A

Promote cell proliferation

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6
Q

How is amplification occuring at each stage of the MAP kinase cascade

A

Each kinase can activate multiple kinases etc etc

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7
Q

How could an issue with a kinase pathway lead to cancer?

A

If the pathway was permanently activated, all steps including the activation of proteins and transcription factors involved in cell proliferation would go on unmitigated–> uncontrollable cell division

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8
Q

What is an oncogene?

A

A muated gene that has the potential to cause cancer

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9
Q

What is a proto-oncogene?

A

Unmutated genes which affect cell proliferation (and could turn into oncogenes if mutated)

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10
Q

Why could the Ras genes and the MAPK genes be considered proto-oncogenes?

A

They are both eventually involved in cell proliferation, and could mutate

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11
Q

How is phosphorylation status a signalling switch?

A

The phosphorylated form of some proteins is the active form, while the dephosphorylated form is the inactive form

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12
Q

What catalyses the turning off of a phosphorylated, activated protein?

A

Protein phosphotase

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13
Q

Where does PI3kinase bind to in the PI3K pathway?

A

The phosphotyrosine onto HER3

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14
Q

What happens to PI3K after it docks onto the phosphotyrosine on HER3?

A

It is activated

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15
Q

What type of kinase is PI3K?

A

A lipid kinase

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16
Q

What does PI3K uses PIP2 for?

A

As a substrate to generate PIP3

17
Q

Where are PIP2 and PIP3 found?

A

Membrane bound

18
Q

What do some protein regions of proteins such as protein kinase 1 and Akt allow?

A

High affinity binding to PIPs

19
Q

What are the domains that allow certain proteins to bind to PIPs?

A

Pleckstrin Homology Domains

20
Q

What do Protein kinase 1 and Akt use PIP3 as?

A

A docking site, allowing them to be brought to the plasma membrane

21
Q

What does protein kinase 1 do to Akt once they are both at the plasma membrane?

A

It phosphorylates, and activates it

22
Q

What does Akt do immediately after being phosphorylated?

A

It dissociates from the PIP and the plasma membrane

23
Q

What process is Akt important in?

A

Cell survival

24
Q

What is active Akt?

A

A serine/threonine kinase

25
Q

What does active Akt do to Bad?

A

Akt phosphorylates Bad

26
Q

What does Bad do in its active form?

A

It holds Bcl2 in its inactive state

27
Q

What does the phosphorylation of Bad do?

A

Changes Bad’s conformation, causing it to release Bcl2

28
Q

What does the release of Bcl2 from bad to to Bcl2?

A

Activates it

29
Q

What is the role of active Bcl2

A

Promotion of cell survival by inhibition of apoptosis

30
Q

How does active Akt mediate cell growth?

A

Through other signalling events, it ends up activating mTor

31
Q

What does mTor do once activated?

A

Inhibits protein degradation and stimulates protein synthesis

32
Q

Where does phospholipase C gamma bind to?

A

A phosphotyrosine of HER3

33
Q

What does phospholipase C gamma use PIP2 for?

A

As a substrate to generate DAG (diacyl glycerol) and IP3 (inositol triphosphate)

34
Q

Where is IP3 sent after it is generated?

A

To the cytosol

35
Q

What does IP3 do once it is in the cytosol?

A

It binds to, and opens calcium channels in the ER

36
Q

What is the direct effect of IP3 binding to Ca2+ channels on the ER?

A

The cytosolic concentration of Ca2+ increases

37
Q

What does DAG do once generated?

A

Recruits and activates protein kinase C (PKC)

38
Q

What can cytosolic ca2+ bind to?

A

PKC

SL12002 Cell Biology (14 decks)

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