cytokine action

Question 1

what does DNA damage lead to?

Answer 1

activation of p53 transcription factor through phosphorylation

Question 2

describe the process of DNA damage?

Answer 2

1) leads to activation of the p53 TF through phosphorylation
2) ATM/ATR and Chk1/Chk2 kinase pathway
3) releasing the Mdm2 block
- p21 CDK inhibitor is expressed
- creates negative feedback on G1/S and S cyclin/CDK

Question 3

where was 14-3-3 proteins identified?

Answer 3

bovine brain homogenate resolved in starch-gel electrophoresis at the 14th fraction at position 3-3

Question 4

describe 14-3-3 briefly

Answer 4

• 30 kDa
• form dimers (homo and hetero)
• mammals have a, b, y, e etc
• involved in signal transduction
  eg. cell division, apoptosis and differentiation

Question 5

what is the c-Ras motif?

Answer 5

RSx-pS-xP

Question 6

how does library screening of 14-3-3 work?

Answer 6

• immobilise 14-3-3 on beads
• add peptide library
• wash
• sequence retained peptides

Question 7

what are the two binding motifs that peptides can bind to 14-3-3?

Answer 7

1) cis-pro
2) trans-pro

Question 8

how do you identify strong binders by random peptide libraries?

Answer 8

• anchor residue: phosphoserine
• flanking sequences varied
• crystal structure validates binding mode
• SPR to check affinity

Question 9

what does active Ras GTP trigger?

Answer 9

activation of raf

Question 10

what does HIV Nef stimulate?

Answer 10

MAP cascade by Raf interaction