MARIA - LECTURE 7 Flashcards
why must the levels of iron be tightly controlled?
what are the two proteins in the cell that control iron availability?
how is Ferritin mRNA translation controlled in low vs high iron concentrations?
how is Transferrin mRNA translation controlled in low vs high iron concentrations?
how do retroviruses perform frameshift to control their translation
what happens to the ribosomes on mRNAs during stress
they pause, elongation is stopped
where do repressed mRNAs accumulate?
in processing bodies and stress granules
what is the composition of stress granules
what is the composition of P bodies
what are the characteristics of the mRNAs present in stress granules and P bodies?
why do mRNAs localize?
what is the machinery (proteins) involved in mRNA localization
what is the zipcode on the mRNA
sequence or structure in the RNA, usually present in the 3’ UTR
what do the RNA binding proteins do
what do molecular motors do
transport mRNPs on cytoskeleton (actin or microtubules)
how does translation activation happen in mRNA localization
de repression of translation and anchoring of mRNA
how does Ash1 mRNA localization in S. cerevisiae work
Ash1 is a transcription factor that localizes to the nucleus of the daughter cell during budding to preserve the correct mating type (alpha or a)
1. zipcodes mainly in 3’ UTR but also CDS of the mRNA
2. recognition by She2
3. She2 binds to She3
4. She3 binds to Myo4
5. translational silencing through Puf6 and Kdh1 binding
6. molecular remodeling in daughter cell:
- release of She2 from the complex
- anchor factors associate with ASH1 mRNA
- phosphorylation and release of Puf6 and Kdh1
- translation of ASH1 mRNA
- Ash1 enters daughter nucleus
what is an example of mRNA localization in mammalian cells
actin beta mRNA localizes at axonal terminals and dendritic spines in response to synaptic stimulation
few things are known about mRNA transport in neurons
transported together with ribosomes and other necessary components in neuronal granules
what are the four ways we identify zip codes and RNA binding proteins (RBPs)?
summary of mRNA localization and localized translation
what are other mechanisms of mRNA localization
localization by protection from degradation
localization by cooperation of signal peptide and zipcode
mRNAs catch a ride with organelles
mRNA catch a ride with other mRNAs by sequence complementarity
what are the three mechanisms of mRNA surveillance?
non-sense mediated decay (NMD)
non-stop decay (NSD)
no-go decay (NGD)
what are the signs that lead to one of the three mRNA surveillance mechanisms?
how does non-sense mediated decay work
how does no-stop decay work?
what are the things that lead to no-go decay?
how does NGD work
Hel2=ZNF598 in mammals
