L18 Eukaryotic Gene Regulation

Question 1

Gene product function can be controlled

Answer 1

see onenote

• protein assembly
• protein targeting
• protein processing and modification

Question 2

Protein modification

Answer 2

see onenote

• phosphorylation and desphosphorylation
• uses ATP
• can change ON/OFF state

Signal leads to cascade of phosphorylation which leads to response e.g. transcriptional changes that copes with whatever the stimulus needs - growth hormone => cells will divide

Not a linear path, it is a network

Question 3

Gene expression in yeast

Answer 3

see onenote

Secrete pheromone to tell their neighbours whether they are “a” or “alpha”
If pheromones detected they will mate
Pick up pheromone by membrane receptor
If the pheromone is detected, they will grow towards each other, schmoo => cell fusion => 1 cell, 2 nuclei (haploid => diploid)
Diploid can undergo meiosis
Breaks out of the “bag” and back to vegetative growth

Question 4

Cell types table

Answer 4

see onenote

Question 5

Mating signalling cascade

Answer 5

see onenote

Question 6

Ligand-receptor interaction

Answer 6

see onenote

Question 7

Ligand binding

Answer 7

see onenote

GTPases (G proteins)
Effector proteins:
- GAP
- GEF
- GDI

Question 8

Protein Processing

Answer 8

• proteolytic cleavage
• specificity driven by specific protease gene expression

Different proteases cleave differently
One protein => different protein products

Question 9

Translational control

Answer 9

see onenote

• multiple levels
• stable but not translated until required

Question 10

Global control of translational initiation - mTOR kinase

Answer 10

see onenote

mTor kinase

4E-BP inhibits translation
Tor phosphorylates 4E-BP so that it can no longer interact with e14E and translation can occur

Question 11

Specific control of translation initiation - Fe

Answer 11

see onenote

Iron homeostasis

• iron regulatory protein (IRP)
• iron regulatory element (IRE), forms loop through base pairing
• Fe2+
• IRP binds IRE and blocks E1F4F function => no translation

+Fe2+
- IRP cannot bind to IRE and initiation proceeds normally

Question 12

Post-transcriptional control

Answer 12

mRNA stability

• RBC
• A.nidulans nitrogen metabolite repression

mRNA translatability

Question 13

mRNA stability - A.nidulans nitrogen metabolite repression

Answer 13

see onenote

• areA gene produces +ve acting transcriptional regulator
• AreA required for use of non-preferred nitrogen sources