Figure 4.

Model of relations between the proteins encoded at the het-s locus. The het-S allele encodes a protein that can form complexes with the pHET-s polypeptide; coexpression of the two proteins triggers the incompatibility reaction. The het-s allele encodes the pHET-s* polypeptide, which is not reactive in incompatibility, and can be converted into a structurally different form, the prion form pHET-s, which is reactive against pHET-S, and can catalyze the conversion of pHET-s* to the pHET-s conformation.