Dimeric alpha-amylase inhibitors expressed in Butte 86. N-termini of 0.53 and 0.19 type WDAI determined by Maeda et al. [24, 25] are indicated by the bracket. The single amino acid difference between WDAI Bu-1 and WDAI Bu-2 is enclosed in a box. Peptides obtained by MS/MS that distinguish individual WDAI are enclosed in shaded boxes. Total MS/MS coverage of WDAI Bu-1 and WDAI Bu-2 in protein spot 312 from Dupont et al.  was 74%, coverage of WDAI Bu-3 in protein spot 283 was 68%, and coverage of WDAI Bu-4 in spots 286 and 283 was 77% and 60%, respectively (Additional file 5).