Cell Cycle 3 Flashcards
What are the Oncoproteins from Adenovirus?
E1A, E1B
What is the weight of retinoblastoma?
105kDa
What proteins are similar to Rb?
p107 and p130
When hypo-phosphorylated, what transcription factor is Rb bound to to prevent its function?
E2F
Whats releases E2F?
CyclinD/cdk4 or 6
or E7, E1A
What are transcriptional targets of E2F?
Cdk1, PolA, DHFR, E2F1, Cyclin A
What is DP?
The dimerisation partner of E2F
What sites are there in E2F?
Cyclin binding, DNA binding, Dimerisation, Transactivation, Rb binding
What is the E2F target sequence?
TTTCGCGC
What phases is E2F active in?
G1 and S phases - cyclin A promotes destruction of E2F, hence the cyclin binding site
What is the ‘go’ signal for the restriction point?
phosphorylation of Rb and release of E2F
What are the domains in RB?
N terminal domain, A domain, Spacer, B domain, C terminal domain
What motif do oncoproteins use to bind to domain B of Rb?
LxCxE
Can E2F bind DNA when bound to Rb?
Yes
Does Rb interact with:
a) HDAC
b) HAT
HDAC
Does E2F interact with:
a) HDAC
b) HAT
HAT
What is BRG1 and what is the relevance to the restriction point?
ATP dependant chromatin remodeller. Can slide nucleosomes along DNA and can loosen or tighten DNA
What does cyclinD/cdk4 phosphorylate on Rb?
Residues in CTD
What happens directly after phosphorylation of CTD of Rb?
Interaction between CTD phosphates and lysines in binding pocket (ASB)
This cases dissociation of HDAC from B domain and exposes ser-567
What does loss of HDAC from Rb allow?
Expression of cyclin E - under promoter sensitive to chromatin structure - HAT is still bound to loosen chromatin
How does cyclin E/cdk2 contribute towards the release of E2F?
Phosphorylates Ser-567, only available when Rb is in kinked conformation - this frees E2F
When does BRG1 dissociate from Rb in the phosphorylation pathway?
It does not need to
What oncoproteins have structural similarities to E7?
E1A, large T antigen
