FIG. 2.

Mutations introduced in the S gene. The WT sequence corresponds to the last 9 residues of the pre-S2 domain and to the first 29 residues of the WT S protein (subtype ayw; EMBL accession no. X02496). The position of the TM1 domain was defined between amino acids P174 and P192 according to the TM prediction software programs PHDrhtm (52) and NORSp (38). It is important that the position of the TM1 domain varies depending on the prediction software used and that several positions are found in the literature (2, 3, 6, 13, 18, 47, 48). The dotted lines delimit the putative fusion peptide from amino acids M164 to R187 (50) and the PEST sequence, which spans the last 7 residues of the pre-S2 domain and the first 6 of the S domain (39). Deleted amino acids are replaced by dots in the mutated protein sequences. Alanine substitutions are highlighted in gray. Deletions (Δ) are inclusive, and residues are numbered according to their respective positions relative to the first N-terminal amino acid of the L protein. In series 2 and 3, the S indicates that alanines were substituted for all amino acids in the range specified. For the unique and double substitutions, we used the classical writing convention to indicate the mutation. HC, hydrophobic cluster.