Fig. 1.

M156 inhibits rabbit but not human PKR in yeast. (A) Multiple sequence alignment of MYXV-Lu M156, VACV K3, and human (h) eIF2α. Conserved residues are highlighted in yellow (100% conservation) or purple (identical with M156). The methionine encoded by the putative start codon of the predominant M156 isoform is shown in red. An asterisk indicates L98 in MYXV-Lu M156. Plasmids encoding VACV K3, MYXV M156, or empty vector under the control of a yeast GAL-CYC1 hybrid promoter were transformed into isogenic yeast strains, which have either empty vector (control) (B), human PKR (C), or E. rabbit PKR (D) stably integrated at the LEU2 locus under the control of the GAL-CYC1 promoter. Transformants were colony purified and grown under inducing conditions at 30 °C for 4 d. Results shown are representative of four independent transformants for each plasmid. (E) Transformants described above were grown in liquid SC−Gal medium for 4 h to induce expression. Whole cell protein extracts were obtained from equal numbers of cells and subjected to Western blot analyses. The blots were probed with phospho-specific antibodies against Ser51 eIF2α (eIF2α-P), then stripped and probed with polyclonal antiserum against total eIF2α.