FIG. 1.

ORF organization and expression of the SeV P gene. The ORFs expressed as protein (P, C, V, and W) are shown as horizontal boxes, drawn roughly to scale (above). Several domains of the P protein, that which chaperones unassembled N protein (N°), its tetramerization domain including the L protein binding site, and that which binds to the N:RNA nucleocapsdid, are indicated. The double-headed arrow shows the editing site (codon 317), where G residues are added cotranscriptionally, to access the V and W ORFs. A blowup of the 5′ end of the mRNA is shown in the middle, and the five ribosomal start sites in this region are indicated. The numbers refer to the codon positions of the P and C ORFs. For the C ORF, the AUG¹¹⁴-initiated C protein is the point of reference; hence, the ACG⁸¹-initiated C′ protein begins at position −11. All four C proteins terminate at codon 205. The 18-nucleotide deletion that eliminates codons 13 to 18 of P and codons 10 to 15 of C is shown, along with the N chaperone site of P. An alignment of residues −9 to 19 of the C ORF with residues 273 to 300 of the reovirus ς3 protein (part of the dsRNA binding motif) is shown at the bottom. The five basic residues essential for dsRNA binding are indicated with asterisks.