Figure 2.

Temperature-sensitive phenotypic analysis of the UPR-inducing kar2 mutants. Serial dilutions from log-phase cultures of the wild-type and the indicated mutant strains were inoculated on rich medium and incubated at the indicated temperatures for 3–6 d. The relative strength of UPR activation in the various mutants at 30°C is also indicated; –, no activation; + to +++, varying degrees of UPR activation as determined by the length of time required for the mutant colonies to turn blue in agar-overlay plate assays for β-galactosidase activity (see MATERIALS AND METHODS for details). The nomenclature of the mutants in this figure does not correspond to previously isolated kar2 mutant alleles, but the amino acid position(s) and predicted substitution(s) in the mutant alleles are indicated. Nucleotide substitutions that do not change the encoded amino acid sequence from the wild-type allele (i.e., silent mutations) are not shown. ND, DNA sequence analysis of the mutant allele was not completed.