PRNP and fatal familial insomnia: One protein that is subject to Ub-mediated proteolysis is the prion protein PrP [8], [9], [10], [11], the scrapie form of which (PrPSc) is a causative agent in transmissible spongiform encephalopathies (TSEs) or prion disorders that include fatal familial insomnia, Kuru, Creutzfeltd-Jacob disease, scrapie in sheep and mad cow disease [12], [13].