RNA modifications - lecture 17 Flashcards
What molecule was used to learn about RNA modifications?
tRNA
What are wobble - position modifications?
34 , first position of the anticodon. the wobble position means it can bind to different sequences on the code. E.g G can interact with C and U
What is a common mitochondrial mutation in methionine tRNA?
5 - formylcytosine
What enzyme is needed to convert methionine rTNA in to 5 methyl cytosine?
NSUN3
What enzyme is needed to convert 5 methyl cytosine to 5 formylcytosine?
ABH1
What is he most common mutation in mammalian mRNA?
N6 - methyl adenosine (m6A)
How is the M6A mutation mapped?
- fragment the mRNA
- Use and antibody thats been raised to the modification
- Wash away any antibody thats unbound , isolate the modifications
- Know which fragments have the M6A modification , can sequence these fragments
What do the proteins YTHDF1 and YTHDF2 bind to?
M6A modification
What does YTHDF1 do?
regulates its translation , speeds it up
What does YTHDF2 do?
Results in a decay of the mRNA
What is a less common modification in mRNA?
5 - methyl cytosine
What are older ways to detect 5mC in mRNA?
- bisulphite sequencing ( not very good get a lot of false positives)
- Raise an antibody to the modification
What are newer ways to detect 5mC in mRNA?
- express the enzyme which catalyses the modification , this forms a covalent bond
- Freeze that complex, map where the covalent bond has formed
Where does the methylation of cytosine most commonly occur? what sequence
CTCCA , Methylation on the first C.
Methylation found in 3 prime UTR too most commonly
How do you form inosine bases?
Enzymatic modification of adenosine bases
