Fig. S2.

Repeat expansions in the YLR177W PrLD. (A) Short segments lacking any prion-inhibiting amino acids were identified in the YLR177W PrLD (indicated as α, β, γ, and δ in the PrLD sequence). (B) Versions of the YLR177W PrLD containing varying numbers of repeats of each segment were made. These repeat expansion mutant PrLDs were fused to Sup35MC and tested for prion activity. For each construct, the region replicated and the copy number of the repeats are indicated. PAPA scores of each PrLD-Sup35MC fusion are indicated in parentheses. For the γ segment, four and five repeat versions were designed; however, cells expressing these fusion proteins as the sole copy of Sup35 were inviable. For the δ4 segment, it is unclear why fewer Ade⁺ colonies were seen upon PrLD overexpression. This may reflect toxicity of this overexpressed PrLD, particularly in prion-positive cells. Alternatively, the overexpressed PrLD may preferentially form structures that are poorly propagated.