lecture 8 recap Flashcards
RNA editing is
nucleotide alterations which result in different or additional nucleotides in the RNA
what are the 2 classes of editing
insertion/deletion
base modification
can flip purines e.g.
A to I (I is same as G) by deamination
can flip pyrimidines e.g.
C to U via deamination
mRNA can create
start codons by inserting a U (AUG)
N6-methyladenosine causes a methyl group to be added to an
A (m6A)
writers
add methyl groups
readers
recognise the methyl groups
erasers
remove the methyl group
writer example
Mettl3
reader example
Hu-R, YTHDF1-3
eraser example
FTP, AKLBH5
what does the m6A cause
sometimes reader protein only recognises the
mRNA when its methylated or sometimes m6A blocks the reader protein
can either make the mRNA more stable or can cause a target for degradation of the mRNA depending on
the mRNA and the protein it recruits
cytosine deaminated is
uracil
adenosine deaminated is
inosine (recognised as guanine)
UAA is a common
stop codon
if you change the C in CAA to U you will get a smaller protein
an A to I change in the glutamate receptors causes Q (glutamate) to change to
R (argenine)
occurs in L-glutamate major excitatory neurotransmitter which normally lets through sodium and calcium, editing decreases
calcium permeability, channel signalling is reduces
this editing is carried out by
ADAR2 gene
methylation of 2 ribose from OH group (2-0-methylation) changes property of ribose by stabilising what
5’ end of DNA
the nuclear pore:
on the nucleoplasmic side theres a
cage structure
on the cytoplasmic side there are
filaments
RNA is an acid meaning tis charged and the pore is hydrophobic meaning
RNA wont go through on its own
tRNA export factor is
Exp-t
miRNA export factor is
Exp-5
snRNA binds to a
cap binding complex
it then gets exported by
PHAX
PHAX binds to
CRM1 which exports proteins
mRNA binds to
CBC (cap binding complex) and ALY/Yra1
this allows it to bind to which export proteins
TAP/Mex67 and p15/Mtr2
