Saccharomyces cerevisiae is an occasional host to an array of prions, most based 
on self-propagating, self-templating amyloid filaments of a normally soluble 
protein. [URE3] is a prion of Ure2p, a regulator of nitrogen catabolism, while 
[PSI+] is a prion of Sup35p, a subunit of the translation termination factor 
Sup35p. In contrast to the functional prions, [Het-s] of Podospora anserina and 
[BETA] of yeast, the amyloid-based yeast prions are rare in wild strains, arise 
sporadically, have an array of prion variants for a single prion protein 
sequence, have a folded in-register parallel β-sheet amyloid architecture, are 
detrimental to their hosts, arouse a stress response in the host, and are 
subject to curing by various host anti-prion systems. These characteristics 
allow a logical basis for distinction between functional amyloids/prions and 
prion diseases. These infectious yeast amyloidoses are outstanding models for 
the many common human amyloid-based diseases that are increasingly found to have 
some infectious characteristics.