L9-10: Post transcriptional control of gene expression II

Question 1

ribosome

components?

Answer 1

natural ribozyme doing more than phosphoidester bond shuffling

1/3 protein
2/3 RNA

Question 2

pro vs euk ribosomes

Answer 2

euk> 80S (30S and 50S)
pro> 70S (40S and 60S)

eukaryotic ribosomes are more complex

Question 3

components of tRNA

Answer 3

TC loop
variable loop
anticodon
anticodon loop
D loop

in P/A sites / delivers aa

Question 4

charging of tRNA

catalysis?

Answer 4

1. aa activation> aa/ ATP bind catalytic site
2. nucleophilic attack by alpha carboxylic acid aminoacyl adenylate (aa-AMP)
3. hydroxyl group of adenine 76 of tRNA attacks carbonyl carbon of adenylate&raquo_space; aminoacyl-tRNA / AMP

catalyzed by amioacyl-tRNA synthetases

peptide bond formation catalyzed by ribozome

Question 5

translation catalysis

Answer 5

by RNA

Question 6

translation elongation

driver?

Answer 6

Aminoacylated tRNA binding site A
ribosome moves along 3 bases to bring next codo into A site
moves into polypeptide chain site P where expanding polypeptide chain is attached

elongation factor G drives

RNA-catalysed event

Question 7

elongation factor G in eukaryotes

Answer 7

eEF2
drives translational elongation

Question 8

peptide bond formation

Answer 8

catalysed by ribosome

Question 9

eukaryotic translation initiation

Answer 9

small sub-unit binds CAP
scans AUG to start
initiating methionine

Question 10

kozak consensus sequence

Answer 10

most frequently found around AUG

Question 11

mRNA circularization requirements

Elf4F complex

Answer 11

elF4E (G cap binding)
Elf4A (ATPase/ RNA helicase)
Elf4G (binds ElF4E/A/3/PAB)

requires elF4E/ G / PAB

Question 12

mRNA circularisation function

Answer 12

monitors mRNA integrity
moves ribosomes ending translation close
key tln factors

Question 13

Elf1A

Answer 13

80S dissociation/ met-tRNA binding to 40S

Question 14

Elf!

Answer 14

AUG recognition

Question 16

ElF5

Answer 16

stiumlates ElF2 GTPase
GAP for Elf2

Question 17

Elf3

components/ function

Answer 17

mutlifactorial complex of ElF1A/ElF1/ElF5
prevents 60S binding

Question 18

ternary complex

Answer 18

Met tRNA in complex w initiation fcator/ ElF2 and GTP

Question 19

ElF2

Answer 19

binds ElF 5
met-tRNA binding
GTPase

needs to be recycled for ternary complex generation > further initiation

Question 20

48S PIC

Answer 20

small sub-unit primed for mRNA association

binds to ElF4G w ElF4E/4A

Question 21

43S association requirements

Answer 21

1. ElF3/4G interaction
2. RNA unwinding > ElF4F (4A)

Question 22

which elf binds cap

Answer 22

ElF4A
also works w PAB to circularize

Question 23

translocation in eukaryotic translation

Answer 23

required for mRNA/tRNA movement through ribosome

Question 24

when does translation regulation occur?

Answer 24

initiation

Question 25

translation regulation stages

Answer 25

1. ElF4F binding on mRNA 2. 43S binding 3. ElF2B/ ternary complex formation - drives ElF2 cycle/ regulation

Question 26

ElF2 cycle/ regulation

Answer 26

- ElF2 leaves small sub-unit

Question 27

Iron response elements IRE

Answer 27

hairpin loops w conserved loop sequence and bulge in stem 5'/3" UTRs of Fe-regulated RNAs bound by Fe regulatory proteins IRP1/2

Question 28

IRPs in low Fe

Answer 28

IRPs 1/2 bind to IRE of 5' UTR decreases expression of proteins in storage " bind 3' UTR stabilise RNAs as targets for ribonucleases mRNA stabilized

Question 29

IRPs in high Fe

Answer 29

IRP1/2 deactivated - 2 degraded - 1 binds to FeS clusters / prevents IRE binding > RNA release | translation of target proteins ## Footnote transport protein mRNA degradation

Question 30

IRP1

Answer 30

bifunctional protein binds FeS clusters in high iron > no RNA binding / becomes c-aconitase

Question 31

c-aconitase

Answer 31

interconverts citrate and isocitrate

Question 32

ElF2b

Answer 32

controls active ElF2-GTP levels/ initiation rate decreases w stresses ElF2 phosphorylation regulates/ comp inhibits ElF2b> ternary complex impairment/ decrease in mRNA initiation | lower level than ElF2

Question 33

ElF2 sub-units

Answer 33

alpha/ beta/ gamma alpha> phosp on ser51 by PKRI/PERK/GCN2/HRI Beta> binds 2b/5 gamma GTPase/ met-tRNA kinase

Question 34

ElF2 kinases

Answer 34

PKR PERK GCN2 HRI | dimerize under stimulatory conditions/ autophosphorylate and act on subs

Question 35

PKR activation

Answer 35

by dsRNA viral infection

Question 36

PERK

Answer 36

Mediator of unfolded protein response/ ER stress

Question 37

GCN2

Answer 37

regulator of tln in response to aa availability

Question 38

HRI

Answer 38

links globin availability to protein synthesis

Question 39

2 PKR domains

Answer 39

regulatory kinase

Question 40

PKR expression

Answer 40

low expression normally increases w interferon exposure | viruses release

Question 41

iron metabolism regulation

Answer 41

Fe levels regulate iron storage/ transport protein expression | haem/ FeS clusters for redox/ gene exp

Question 42

UTR

Answer 42

untranslated region 5'/3' can influence translation