Prions

Question 0

Describe the function of normal PrPc proteins

Answer 0

Small cell surface proteins
Normal functions in the brain include:

Neuroprotection against oxidative stress and apoptosis

Cellular uptake of copper ions

Formation and upkeep of synapses

Cell adhesion to the extracellularly matrix

Question 1

Define a prion?

Answer 1

A prion is proteinaceous infectious particle which form insoluble fibrous plaques in the brain tissue of an animal
Prions give rise to Transmissible Spongiform Encephalopathies
Infects sheep and goats (scrapie), cattle (BSE - bovine spongiform encephalitis) and humans (vCJD - variant Creutzfeldt-Jakob Disease) and deer ( CWD - chronic wasting disease)

Question 2

How do prions replicate?

Answer 2

Once inside the host they recruit the hosts naturally occurring PrPc proteins and induce/catalyse a change in conformation which converts them into prion proteins - this is called autocatalytic amplification
The host needs to have the PrPc gene otherwise it cannot develop TSE
The protein is therefore able to replicate itself without the need for DNA - this is called protein inheritance