ABSTRACT
Prions are infectious proteins. In fungi, prions correspond to non-Mendelian genetic elements whose mode of inheritance has long eluded explanation. The [Het-s] cytoplasmic genetic element of the filamentous fungus Podospora anserina ^was originally identified in 1952 and recognized as a prion nearly half a century later. The present chapter will attempt to describe the work on [Het-s] from a historical perspective. The initial characterisation and early genetic and physiological studies of [Het-s] are described together with the isolation of [Het-s] encoding gene. More recent work that led to the construction of a structural model for this prion is also discussed.
