Switches and Cytokines

Question 1

what does EGF bind to ?

Answer 1

RTK (Receptor Tyrosine Kinase)

Question 2

explain the EGF pathway

Answer 2

1) EGF binds to RTK
2) RTK auto- phosphorylates and activates cytosolic kinases
3) The kinases enter the nucleus and phopshorylates TFs
4) this leads to transcriptional activation

Question 3

why is RTK different?

Answer 3

because it is both a receptor and a kinase and therefore when ligand binds it causes receptor dimerisation and activation of itself (the kinase)

Question 4

what is difference between inactive and active RAS?

Answer 4

Inactive: GDP
Active: GTP

Question 5

what does the SH2 domain recognise and where can it be found?

Answer 5

SH2 recognises phosophotyrosine (hence recognising RTK)
can be found on GRB2

Question 6

what does SH3 domain recognise and where can it be found?

Answer 6

SH3 recognises proline rich peptides
can be found on SOS

Question 7

what does phosphorylation on kinases do?

Answer 7

changes structure of the lip domain making them active

Question 8

what are GEFs and give an example

Answer 8

Guanosine exchange factors
eg. SOS

Question 9

What are GAPs

Answer 9

GTPase activating proteins

Question 10

what are RGSs

Answer 10

Regulators of G-protein signalling

Question 11

what are GDIs

Answer 11

Guanone nucelotide dissociation inhibitors

Question 12

describe GTPases

Answer 12

GTP binding proteins
- around 15-25kDa
- 160-180 Amino acids
- have conserved alpha, beta topology (5a and 6b)

Question 13

what are the two switches in GTPase

Answer 13

• G2(T) threonine is the catalyst
  -G3 (DxxG)

Question 14

what and where is the binding motif in GTPases

Answer 14

P-loop (GxxxxGKS/T)

Question 15

what do matrix metalloproteinases do ?

Answer 15

they can mature/ release EGF from membrane proteins

Question 16

what is SPR and what is it used to study?

Answer 16

Surface Plamon Resonance - used to study drug binding
- ligand receptor interactions
- antibody-antigen interactions
- protein-DNA interations

Question 17

describe simply how SPR works?

Answer 17

1) solution of prey molecules (during association - creates ligand receptor binding)
2) buffer wash causes dissociation
over about 10 minutes

Question 18

what deactivates CDK and how ?

Answer 18

Wee1 deactivates CDK by phosphorylation on tyrosine 15

Question 19

what can activate CDK?

Answer 19

CAK activates CDK by phopshorylation on threonine 161

Question 20

what is the process of CDK/ cell cycle control?

Answer 20

1) Wee1 deactivates CDK by phosphorylation on tyrosine 15
2) CAK can activate CDK by phosphorylation on threonine 161
3) Cdc25 activates CDK by dephosphorylation on tyrosine 15
4) CDK activation
5) Rb phosphorylation
6) E2f activation
7) autostimulation
8) Cell cycle progression
9) Further Rb Phosphorylation