Cell signalling 2 better

Question 1

What kind of receptors are receptor tyrosine kinases

Answer 1

An enzyme coupled receptor

Question 2

What is an enzyme coupled receptor?

Answer 2

A receptor that has a cytosolic domain with intrinsic enzyme activity and an extracellular domain where binding occurs

Question 3

What enzyme activity does receptor tyrosine kinases have?

Answer 3

Tyrosine kinase activity

Question 4

What are RTKs used to mediate?

Answer 4

Cell survival, growth and differentiation

Question 5

How do RTKs mediate cell survival, growth and differentiation?

Answer 5

Through growth factor signalling

Question 6

How do RTKs usually exist?

Answer 6

As inactive monomers

Question 7

What does the binding of a ligand do to two RTK monomers?

Answer 7

Brings them together, causing dimerisation

Question 8

What does dimerisation of the RTKs do to the tyrosine kinase domains?

Answer 8

Brings them close together

Question 9

What do the TKDs do once brought together?

Answer 9

Cross autophosphorylate each others tyrosine residues

Question 10

What do TKDs do once phosphorylated?/

Answer 10

Phosphorylate other tyrosine residues outside of the kinase domains

Question 11

What do the phosphotyrosines do?

Answer 11

Serve as docking sites for adaptor/signalling proteins

Question 12

What do adaptor/signalling proteins do?

Answer 12

Propagates the signal to the rest of the cell

Question 13

What is HER2 an example of?

Answer 13

An RTK

Question 14

What does HER2 stand for?

Answer 14

Human epidermal growth factor 2

Question 15

What kind of dimers does HER2 usually form?

Answer 15

heterodimers (i.e. HER2 and another epidermal growth factor receptor)

Question 16

What are some human epidermal growth factors?

Answer 16

HER2, HER3, EGFR, HER4

Question 17

What causes dimerisation between HER3 and HER2?

Answer 17

A ligand binding to HER3

Question 18

What ligand binds to HER3?

Answer 18

Neuroglin

Question 19

What happens after the activation of the HER2 HER3 heterodimer?

Answer 19

Grb2 (adaptor protein) docks onto one of the phosphorylated tyrosine kinases from HER2

Question 20

What can Grb2 also interact with (other than RTK)?

Answer 20

Ras-GEF (aka Sos)( a regulatory protein)

Question 21

What does SOS promote?

Answer 21

Inactive Ras (in its GDP bound state) to release GDP in exchange for GTP, thus activating Ras

Question 22

What happens to Ras after it exchanges its GDP for a GTP?

Answer 22

Ras is activated

Question 23

Where is Ras found?

Answer 23

Membrane bound

Question 24

What can Ras do once activated?

Answer 24

Can be involved in downstream MAPKinase signalling

Question 25

What can happen during HER2 overexpression?

Answer 25

HER2 can form homodimers with itself

Question 26

What happens when a HER2 homodimer forms?

Answer 26

The Ras activation can occur regardless of ligand binding

Question 27

What is Ras?

Answer 27

A monomeric G protein with intrinsic GTPase activity

Question 28

Why does Ras have intrinsic GTPase activity?

Answer 28

So it can hydrolyse GTP to GDP if needed

Question 29

Activity of Ras in its GDP bound state?

Answer 29

Inactive

Question 30

Activity of Ras in its GTP bound state?

Answer 30

Active

Question 31

Ras-GEF stands for?

Answer 31

Ras-Guanine Exchange Factor

Question 32

What does Ras GEF do?

Answer 32

Promoted ras to release GDP and take up a GTP

Question 33

How is Ras activated?

Answer 33

By exchanging its GDP for a GTP

Question 34

How is Ras inactivated?

Answer 34

By using its intrinsic GTPase activity to hydrolyse its GTP

Question 35

What is the role of Ras-GAP?

Answer 35

It promotes the hydrolysis of the GTP in Ras GTP

Question 36

Easier name for MAP kinase kinase kinase??

Answer 36

Raf

Question 37

What does MAP stand for?

Answer 37

Mitogen-activated protein

Question 38

What does Ras (GTP) do to Raf?

Answer 38

Activates it

Question 39

What does activated Raf do?

Answer 39

It phosphorylates, and activates Mek