“…The resulting recombinants had the following modifications (for amino acid sequences see Table 1) : R1 had the initiating methionine codon of its VP replaced with a stop codon, and would therefore be expected to produce no VP ; R2, R3 and R4 produced VPs with BeMV sequences of different sizes and positions at their N termini. The N terminus has been shown to be a major antigenic determinant in TYMV (Pratt et al, 1980), and was predicted by PP to be accessible ; R5 and R6 produced VPs with the predicted αA and αB helices, respectively, replaced with those of BeMV, although the hydrophobicity moment and PP analyses suggested that the αB helix was only partly within the region changed in the R6 recombinant ; R7 produced a VP with the region of the TYMV VP that cross-linking studies had shown to interact with the viral RNA (Ehresmann et al, 1980) replaced with that of BeMV ; ' R8 ', was a point mutant with a lysine residue found in all sequenced tymovirus VPs changed to asparagine. R9 produced a VP with a surface loop region of the TYMV VP adjacent to the R8 lysine replaced with that of BeMV.…”