Figure 2.

Curing of the [RNQ⁺] prion is caused by mutation at a single genetic locus. (A) Biochemical analysis of recessive mutations that cure [RNQ⁺]. The red [rnq⁻] cells carrying recessive mutations created by EMS were mated to a strain carrying wild type Rnq1p in the [RNQ⁺] state. The resulting diploids were sporulated and the solubility of the Rnq1 protein from individual haploids was analyzed as described in the legend of Figure 1. A single representative tetrad is shown. A minimum of eight tetrads were tested for each mutant. (B) Analysis of dominant mutation that cure [RNQ⁺]. The red [rnq⁻] cells carrying dominant mutations created by EMS were mated to a strain carrying wild type Rnq1p in the [RNQ⁺] state. The resulting diploid was sporulated and haploid progeny of this cross were then backcrossed to strains carrying wild type Rnq1p in the [RNQ⁺] state. The resulting diploids from these matings were lysed and fractionated as above. Three tetrads were tested and a single representative tetrad is shown.