Translation II: from polypeptides to proteins

John Stanton-Geddes
15 November 2013

www.johnstantongeddes.org

Overview

Part 1) How do polypeptides become proteins?

  • post-translational modification
  • polypeptide coils and folds
  • assembly with other polypeptides


Part 2) Solving a medical mystery

Review: protein synthesis

17.19

The mRNA sequence

5` CUAGACUAC 3'

encodes the polypeptide 

Leu-Asp-Tyr

If the first C is deleted, what new amino acid will be produced?

  1. Asp-Tyr
  2. Leu-Asp
  3. Leu-Asp-Tyr
  4. Tyr
  5. Nothing

17.05

Prokaryotes

17.25

Modification of mRNA

  • eukaryotes only

17.10

Splicing

17.13

Export

17.26

Targeting polypeptides to specific locations

17.22

Protein Folding

protein folding

http://en.wikipedia.org/wiki/Protein_folding

Chaperones help proteins fold

chaperone

Mis-folded proteins marked for destruction

ubiquitin

A medical mystery

Warning: this video addresses serious medical and cultural issues that are disturbing to watch. You are free to leave if it makes you uncomfortable. The remainder of the class does not require viewing the film.


Kuru: the science and the sorcery


Work on case study in groups of 4.

Kuru

What do you believe is the most likely explanation for this disease?

  1. Genetics (e.g. sickle cell anemia)
  2. Environmental (e.g. exposure to toxins)
  3. Epidemic
  4. Other

A medical mystery: solved!


Historical epidemiology: where did kuru come from?


What causes kuru

Prions

prion protein

http://en.wikipedia.org/wiki/PRNP

Bovine spongiform encephalitis

BSE

http://en.wikipedia.org/wiki/Prion