FIG. 4.

[SP14⁺] variants show frequent interconversion and higher spontaneous conversion in a [RNQ⁺]-dependent manner. (A) [SP14⁺] cells were plated on YPD (1st streak). A single strong [SP14⁺] variant and a single weak variant were isolated (as indicated by the arrows) and replated on YPD (2nd streak) to analyze variant stability. (B) Red colonies expressing SP5 and SP14 in [rnq⁻] cells remained red on YPD and were stable as [prion⁻]. (C) Red colonies expressing SP5 and SP14 in [RNQ⁺] cells gave rise to pink colonies and frequently converted to [PRION⁺].