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CMB2001 > RNA editing > Flashcards

RNA editing Flashcards

1
Q

what is RNA editing

A

nucleotide alteration which results in different or additional nucleotide

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2
Q

where does editing occur

A

mRNA, tRNA and ribosomal RNA (rRNA)

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3
Q

what are the two classes of editing

A

-insertion/deletion
-modification (e.g A to I)

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4
Q

What is the effect of editing

A

Change the coding sequence and/or properties of mRNAs

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5
Q

What can be a base modification which produces ‘marked nucleotides’

A

methylation

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6
Q

Base modification can alter activity, how?

A
  • Additional H bonding potential
  • NH2 can be converted to O and therefore have different properties
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7
Q

what are some of the effects of editing on mRNA

A
  • creation of start codon (C->U or U insertion)
  • Creation of new open reading frame (nucleotide insertion or changes in AA which effects splice site
  • creation of stop codon (U insertion, C->U)
  • removal of stop codon (base conversion)
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8
Q

what is the most prevalent internal modification in eukaryotic mRNA

A

N6-methyladenosine

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9
Q

How is conversion to N6-methyladenosine regulated

A

Writers - Mettl3
Readers - Hu-R
Erasers - FTP

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10
Q

what are methyltransferases function

A

stem cell differentiation, circadian rhythm, cell cycle, splicing and more

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11
Q

what is (I_) recognised as guanosine

A

Inosine

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12
Q

What is produced by enzymatic deamination during RNA editing

A

Inosine (from adenosine)
Uracil (from cytosine)

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13
Q

what is the effect of mRNA editing in relation to ApoB

A
  • Intestine there is editing so C->U
  • Liver there is no editing
  • no editing means that LDL-receptor binding section is translated producing ApoB-100
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14
Q

What is the type of editing of ApoB-48

A

Cytidine deamination

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15
Q

what carries out ApoB editing?

A

APOBEC-1 found in intestine which is linked to cholesterol control, cancer development and inhibition of viral replication

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16
Q

What is the difference between Apo-B-48 and ApoB-100

A

ApoB-100 has an LDL-receptor binding domain whihc is linked to atherosclerosis

17
Q

what is the difference between Q and R site of glutamate receptor

A

Q- allows transport of both Na+ and Ca2+
R- only transport of Na+

18
Q

What is the editing involved in the differentiation of Q/R sites

A

adenosine deaminase by ADAR2

19
Q

what is the effects of mutations in mouse ADAR2 gene

A

lead to seizures, post-natal death, neurodegeneration in the hippocampus

20
Q

What is a modification of ribose

A

2’-O methylation

21
Q

what are the RNAs which contains 2’-O-methylation

A

tRNA, rRNA and snRNA

22
Q

what are the effects of modification of rRNA

A
  • Yeast doesn’t survive without 2’-0-methylation in ribosomal RNA
  • Removal of Y from yeast leads to defects in translation
23
Q

what is mutated in dyskeratosis congenita

A

Human Y synthase

24
Q

How is tNRA transported through the nuclear pore

A

In conjugation with Exp-t and Ran GTP

25
Q

How is miNRA transported through the nuclear pore

A
26
Q

How is tRNA transported through the nuclear pore

A

In conjugation with Exp-t and Ran GTP

27
Q

How is miRNA transported through the nuclear pore

A

With Exp-5 + Ran GTP

28
Q

How is snRNA transported through the nuclear pore

A

CRMI with Ran GTP as well CBC+PHAX

29
Q

How is mRNA transported through the nuclear pore

A

Tap/Mex67 +p15/Mtr2 as well as CBC+ALY/Yral

30
Q

How is rRNA transported through the nuclear pore

A

in a vesicle, CRM1+Arxl+Mex67+Mtr2 as well as Nmd3 with RAN GTP

31
Q

why is mRNA localise

A

-localised protein synthesis
-Generate cell polarity
-prevents expression in the wrong place
- promotes efficiency of subsequent protein targeting
-local control of translation

32
Q

why is local control of translation important

A

synapses

33
Q

why is efficiency of subsequent protein targeting important

A

ß-actin in fibroblasts

34
Q

what are the two methods of localisation

A

Diffusion based
Active transport based

35
Q

how does diffusion based location work

A

free movement + local entrapment

36
Q

how does active transport based localisation work

A
  • Nuclear processing then export
  • RNP remodelling
  • RNP transport using cytoskeleton as vehicle
  • Anchoring then translation

CMB2001 (11 decks)

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