Suppression of the cch1Δ and cnb1Δ mutations by YEpSPA2ΔN. (A) The CCH1 strain bearing YEp351 and the cch1 null mutant (cch1Δ) bearing a multicopy plasmid (either YEpSPA2ΔN, YEpSPA2, or YEp351) were incubated with 6 μM α-factor in SD.Ca100 medium and examined for viability as described in the legend to Fig. 1. Open circles, CCH1/YEp351; filled circles, cch1Δ/YEp351; open triangles, cch1Δ/YEpSPA2; filled triangles, cch1Δ/YEpSPA2ΔN. (B) The CNB1 strain bearing YEp351 and the cnb1Δ mutant bearing a multicopy plasmid (either YEpSPA2ΔN, YEpSPA2, or YEp351) were incubated and examined for viability as described above. Open circles, CNB1/YEp351; filled circles, cnb1Δ/YEp351; open triangles, cnb1Δ/YEpSPA2; filled triangles, cnb1Δ/YEpSPA2ΔN. Note that the wild-type strains CCH1, CNB1, and MID1 are identical to each other. Values are the means ± SD of three independent experiments.