FIG. 3.

Nature and expression of PE38 mutants. (A) Alignment of the PE38 sequences of AcMNPV, B. mori NPV, and OpMNPV. Solid boxes indicate similar amino acids present in all three proteins, shaded boxes indicate similar amino acids present in two of the three proteins, and dashes indicate gaps introduced for optimal alignment. Two arginine-rich regions are indicated with gray overlining. Black and striped overlinings indicate the RING finger motif and leucine zipper, respectively. Open arrowheads show the positions of the PE38D1 and PE38D2 truncated mutants, each initiating at an existing methionine. The asterisks denote amino acid changes made in the conserved residues within the RING finger or leucine zipper domains in mutational analysis of PE38. (B) Immunoblot analysis of the expression of the PE38 mutants. SF-21 cells transfected for 18 h with plasmids expressing genes indicated above each lane were heat shocked to induce gene expression. Cells were harvested 3 h after heat shock. Equal amounts of cell lysates were analyzed by Western blot analysis with anti-FLAG monoclonal antibody. The position of wild-type FLAG-tagged PE38 (42 kDa) is shown on the right.