Receptor mechanism III Flashcards

1
Q

What are growth factor receptors predominately?

A

• Predominantly single transmembrane domain receptors

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2
Q

What does the activation of growth receptors lead to?

A

Activation of receptor Kinases and multiple signalling pathways

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3
Q

Examples of tyrosine receptor kinase

A

Insulin

EGF or PDGF

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4
Q

What are jak/stat and what are they involved in?

A

○ chain of interactions between proteins in a cell
○ Growth hormone

Interferon

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5
Q

Example of serine threonine receptor kinase

A

○ TGFβ

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6
Q

What are enzyme linked receptors involved in the regulation of?

A
○ Cell growth 
○ Division
○ Differentiation
○ Survival
○ Migration
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7
Q

Consequences of inappropriate activation of enzyme linked receptors

A

• Inappropriate activation is associated with disease particularly cancer

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8
Q

What does dimerization do when it comes to tyrosine activity?

A

• Dimerization brings two receptor molecules together allowing phosphorylation of specific tyrosine residues

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9
Q

Can all tyrosine residues be phosphorylated?

A

• Not all tyrosine residues can be phosphorylated

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10
Q

How are phosphotyrosine recognized and what does it lead to?

A

• Phosphotyrosine together with surrounding amino acids are recognised by SH2 domains of other proteins allowing them to bind and undergo activaiton

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11
Q

Result of the activation of tyrosine kinase receptors

A

• Activation of tyrosine kinase receptors activates multiple pathways

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12
Q

What do insulin receptors act on?

A

• Acts on liver and muscle to reduce blood glucose

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13
Q

What do insulin receptors consist of and how are they linked?

A

• Consists of 2alpha and 2beta subunits linked by disulphide bridges

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14
Q

What does the binding of insulin result in?

A

• Binding of insulin results in auto-phosphorylation of 2beta subunits

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15
Q

What does the activation of receptors lead to?

A

• Activation of receptors leads to activation family of small protein substrates called IRS

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16
Q

What does activated IRS activate?

A

○ IRS activates PI 3-kinase which activates PKB

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17
Q

What other substrates do insulin receptors recruit?

A

• Insulin receptor substrate also recruits other proteins such as Ras and Phospholipase C

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18
Q

What leads to the inactivation of receptor kinases?

A

• De-phosphorylation leads to inactivation

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19
Q

What are activated as a result of receptor activation?

A

Phosphates are activated

20
Q

An example of a small G protein

A

Ras is one of a number of small G protein

21
Q

What are small G proteins related to?

A

• Related to Gα subunit of cAMP

22
Q

What are bound to small G proteins

A

Inactive GDP

23
Q

When activated, what happens to small G proteins?

A

When active, it is replaced by GTP helped by GEF

24
Q

What are small G proteins required for?

A

Growth, differentiation and cell motility

25
What activity do small G proteins contain?
• Contains GTPase activity, slow de-phosphorylation helped by GAP
26
What is slow de-phosphorylation helped by?
Helped by GAP
27
In how many percent of human tumors is mutated Ras found in?
30% of human tumors
28
What does the activity of Ras do?
Change GDP to GTP
29
What does activated Ras interact with?
Other proteins including Raf
30
What are activated Ras enhanced by?
Enhanced by GEF
31
What is activated Ras the docking site for?
Activated Ras is docking site for GTPase
32
What does activated GTPase lead to the removal of and what happens to the interaction between Ras and Raf/
• Activated GTPase leads to removal of phosphate to form GDP | ○ RAS and Raf fall apart and is inactivated
33
What can mutations in key regulatory mechanism lead to ?
Can lead to cancer
34
What is Ras in cancers and what does it lead to?
Ras in cancers is mutated and leads to the loss of activity of GTPase
35
What does mutations in phosphatases lead to
It leads to the loss of phosphatases activity
36
Main issues in breast cancer
Over expression in breast cancer
37
What does Herceptin target and what is it used for?
Targets a member of the EGF receptor family and used for the treatment of some cancers
38
What do Jaks do to each other on tyrosines
Jaks cross phosphorylate each other on tyrosines
39
What do activated jaks do to receptors on tyrosine?
They phosphorylate receptors on tyrosines
40
What do STATS dock on to and what happens to them there?
Dock on phosphotyrosines and jaks phosphorylates them
41
What is STAT?
STAT is a transcription factor
42
What do STATs do once they're phosphorylated?
STATs dissociate from the receptor and dimerize via SH2 domain
43
What do the dimers of STAT do?
• Dimer of STAT will bind to specific region of DNA and stimulate transcription of specific protein
44
What activates the smad-dependent signalling pathway?
TGF-beta
45
Basic overview of the smad-dependent signalling pathwat
* Receptor dimerizes * Allows phosphorylation * Smad 2 and 4 phosphorylated * These then dissociate and are recognised and activated by Smad 4 * This will form a dimer that enters the nucleus and bind to specific regions of DNA leading to the transcription of specific genes.