3' end formation of mRNA Flashcards
Which RNAP is the pA-tail specific for?
RNAPII
What is the pA essential for?
1) nuclear export
2) translatability
3) stability
4) transcription termination
What are PAPs?
Poly(A) polymerases
What is the CPSF?
cleavage/polyadenylation specificity factor
What is the CstF?
Cleavage-stimulatory factor
What are CFIm and CFIIm?
Cleavage factors Im and IIm
What is PAB II?
poly(A)-binding protein II
What are the three main steps in processing?
Assembly
Cleavage
Polyadenylation
What specifies the position of mRNA 3’ end?
Signals encoded in the DNA (genome).. these are transcribed into RNA by RNAPII and are recognised by a series of RNA binding proteins and RNA processing enzymes
What are the 2 main multisubunit proteins that recognise the RNA polyadenylation signal?
CstF (cleavage stimulation factor)
CPSF (cleavage and polyadenylation specificity factor)
How do CstF and CPSF access the RNA?
They travel on the CTD of RNA Pol II and are transferred to the 3’-end processing sequence on an RNA molecule as it emerges from the RNA Pol.
Which sequence does CPSF recognise? Which subunit of CPSF recognises this sequence?
The polyadenylation signal sequence: AAUAAA
recognised by the CPSF-160 subunit
Which subunit of CPSF is responsible for cleaving the mRNA precursor just downstream of the polyadenylation signal sequence AAUAAA?
CPSF-73
Which subunits is CPSF composed of?
CPSF-73
CPSF-100
CPSF-30
CPSF-160
Which additional proteins does CPSF recruit to the 3’ region?
Cleavage stimulatory factor (CstF)
Two poorly understood cleavage factors (CFIm and CFIIm)
