iGenetics 3rd Edition by Peter Russell

Exercise 3

Bovine spongiform encephalopathy (BSE; mad cow disease) and the human version, Creutzfeldt-Jakob disease (CJD), are characterized by the deposition of amyloid- insoluble, nonfunctional protein deposits-in the brain. In these diseases, amyloid deposits contain an abnormally folded version of the prion protein. Whereas the normal prion protein has lots of
helical regions and is soluble, the abnormally folded version has
helical regions converted into
pleated sheets and is insoluble. Curiously, small amounts of the abnormally folded version can trigger the conversion of an
helix to a
pleated sheet in the normal protein, making the abnormally folded version infectious.
a. Some cases of CJD may have arisen from ingesting beef having tiny amounts of the abnormally folded protein. What would you expect to find if you examined the primary structure of the prion protein in the affected tissues? What levels of protein structural organization are affected in this form of prion disease?
b. Answer the questions posed in part (a) for cases of CJD in which susceptibility to CJD is inherited due to a rare mutation in the gene for the prion protein.