23

Question 1

when is ribosome rescue needed

Answer 1

no stop codon
truncated or broken mRNA

Question 2

ribosomes reach the end of mRNA without encountering a stop codon

Answer 2

arrested ribosomes- stalled

Question 3

bacterial translation initiation in truncated or full length mRNA

Answer 3

bacteria does not discriminate so we cant not start bc it is truncated

Question 4

eukaryotes translation initiation in truncated or full length mRNA

Answer 4

only starts in intact mRNA but it can break after succesful initiation or mau not contain a stop codon due to faulty splicing

Question 5

3 general events triggered by arrested ribosomes

Answer 5

mRNA decay

protein proteolysis

ribosome recycling

Question 6

what solves stalled ribosomes in BACTERIA

Answer 6

special RNA with proterites of tRNA and mRNA

tmRNA

Question 7

what are the other names of tmRNA

Answer 7

SsrA and 10Sa RNA

Question 8

what does tmRNA do

Answer 8

functions as mRNA by ancoding 10-11 aa peptide

functions like tRNA and can charged with alalnine by AlaRS

Question 9

what does tmRNA function with

Answer 9

SmpB

together they look like tRNA molecule- molecular mimmickry

Question 10

what binds to a stalled ribosomes

Answer 10

SmpB, ananyl-tmRNA, and EFTu GTP

Question 11

what does SmpB, ananyl-tmRNA, and EFTu GTP do in a stalled riboosme

Answer 11

nacsent polypeptide is trnasferred to the alanine on tmRNA

translation switches from original message to a short tmRNA ORF that decodes a degradation tag

Question 12

how is the tagged polypeptide released for degradation

Answer 12

by translation of the ORF nad normal termination

Question 13

what is attatched tot he peptide

Answer 13

the translatioed 10-11 anino acid tag which is the short ORF from tmRNA marking the peptide for degradation

Question 14

what is a common bacterial tmRNA tag

Answer 14

ANDENYALAA

Question 15

what are backup ways bacteria have for resuceing arrested ribosomes

Answer 15

ArfA binds and essentially mimmicks a stop codon so that RF2 binds and releases the peptide

ArfB may releae the peptide directly

Question 16

what are the ways that tarnslation assocaited mRNA quality control pathways detecting aberrent translation events and degrade the faulty mRNAs

Answer 16

nonsense emdiated mRNA decay (NMD)

non stop decay (NSD)

no go decay (NGD)

Question 17

targets mRNAs containing premature stop codons

Answer 17

nonsesnse mediated mRNA decay

Question 18

targets mRNAs lacking a stop codon (premature polyadenylation)

Answer 18

non stop decay

Question 19

targets mRNAs with stalled ribosomes

Answer 19

no go decay

Question 20

ribosome assocatied quality contol

Answer 20

non stop and no go decay

Question 21

how are ribosome associted quality control activated

Answer 21

by the precense of stalled ribosomes

Question 22

what is used in nonsense mediated decay

Answer 22

EJCs

Upf1

Upf2

Upf3

eERF3

Question 23

what is used in ribosome associated quality cotnrol pathwys

Answer 23

pelota (eRF1) and Hbs1(eERF3)

Question 24

what are pelota (eRF1) and Hbs1(eERF3) do

Answer 24

termination factor homologues that rescue stalled ribosomes

Question 25

what are decoding factors delivered to the A site by

Answer 25

in eukaryotes by a specialized member of a subfamily of translational GTPases

Question 26

members of the GTPase subfamily are...

Answer 26

structutally homologues but have non redundant functions

Question 27

acceptance of each decoding factor by the ribosome has

Answer 27

disticnt and irreversible consequences eIF1A- aa addditon by aatRNA eERF3- translation termination by eRF1 Hbs1l- initiation of mRNA and protien qulaity contorl pathwyas by pelota

Question 28

where does NMD function

Answer 28

in one third of inherited disorders and one thrid of acquired disease

Question 29

how can premature stop codons (PTC) occur

Answer 29

genomic mutations error during transcription error during splicing

Question 30

how are premature termination codons recognized

Answer 30

their loaction in mRNA coated in exon junction complexs normal stop codons are downstream of EJC stop codons upstream of EJC likely a premature termination codon

Question 31

NMD sensitive PTC

Answer 31

no full length protein recessively inheted disease

Question 32

NDM insensitive PTC

Answer 32

truncated protein dominantly inherited disease

Question 33

what does transltioan termination at the PTC lead to

Answer 33

SMG1 mediated hyperphosphoryalation of UPF1 faciliated by UPF2, UPF3B and the EJC hyperphosphorylation recruits SMG6 and SMG5/7 to the RNA leading to its degradation by endonucleolytic cleavage, deanenylation and decapping