RNA degradation Flashcards
(41 cards)
why is RNA degradation important
damaged mRNA, incorrectly transcribed/processed mRNA and control of gene expression
where is casein mRNA expressed
mammary gland
Casein mRNA increase _ on stimulation by _
70 fold
prolactin
what is prolactin
hormone promoting milk production
Despite the massive increase in mRNA, transcription only increases 2 fold. How?
half life increase (40 fold), polyA tail length increases & 3’ UTR of RNA binds to proteins which aids stabilisation
Eukaryotic mRNAs is _ during translation
Circular
how does mRNA being circular aid in mRNA integrity being monitors
it will not be circular if it has lost cap or poly (A)
at the 5’ end what is it suggested about the ribsomes
recycled
Closed lopp must be broken before _ can gain access
exonucleases
what are the 2 decapping enzymes
DCP1 & 2
what are the 3 endonucleases enzymes
Argonaute, Swt1 and Smg6
what is the deadenylases
Ccr/Not complex
what are the enzymes that initiate the breakdown of the RNA
- Decapping enzymes
- endonucleases
- deadenylases
what is phase II mRNA degradation
5’ to 3’ & 3’ to 5’ exonuclease
what is the exosome
the main 3’to5’ exonuclease in the cell involved in RNA turnover and processing
what are the 2 nuclease activities involved in the exosome
RRP6 & RRP44
what is the function XRN1
5’ to 3’ exonuclease Involved in RNA turnover and processing & transcription termination
When does XRN1 function
decapping of the mRNA
what are the two types of decay
deadenylation dependent and independent
what stimulates the deadenylase complex
- AU-rich element or ARE
- Nosense codon
- c-fos major coding determinant
- miRNA
how is Rps28B regulated
auto-regulation - negative feedback where it binds to its own message
what works with Rps28B and what does it do ?
Edc3 which is one of several activators of decapping enzymes
give an example of a nuclease targeting specific substrates
PMR1 cleaves albumin mRNA
what is NMD
Nonsense-Mediated Decay
