L20

Question 1

What is an enhancer? An activator? What is mediator?

Answer 1

Enhancer - where activators bind

Activators - protein that activates (e.g. CAP protein)

Mediator - set of proteins that mediates between activator and TBP making it more likely that RNA Pol will bind

Question 2

Give two examples of DNA binding domains found in eukaryotic transcriptional regulators.

Answer 2

Zinc finger, helix loop helix

Question 3

What is a zinc finger?

Answer 3

Zinc finger always bound to Cys and His

Question 4

Different proteins are produced from the α‐tropomyosin gene in different types of muscle. How is this achieved?

Answer 4

Alternative splicing

Question 5

What does a splicing repressor do? What does a splicing enhancer do?

Answer 5

Splicing repressor - less exons in final product

Splicing enhancer - more exons in final product

Question 6

What is a miRNA? What is the protein complex that binds it? What do they bind? What part of the complex (miRNA or proteins) allows it to recognise and bind to this molecule? What happens to the molecule they are binding to?

Answer 6

Micro RNA that binds to RISC protein. They both bind to mRNA as miRNA is the reverse complement of mRNA. Upon binding, either represses translational activity or degrades it.

Question 7

Give two examples of posttranscriptional modification, and what it achieves.

Answer 7

• Disulphide bridges - for folding and stability
• Ubiquitination - addition of ubiquitin protein targets protein for degradation
• SUMOylation - addition of SUMO proteins changes localisation or binding partners
• Glycosylation - for folding, stability and EXTRACELLULAR functions
• Palmitoylation - lipid added to it which allows protein clustering at the membrane for synapse function
• Phosphorylation - activate, deactivate, induce protein-protein interaction