Figure 1. Identification of tomato CYP1 and its interaction with TYLCV V2 in yeast. (A) Amino acid sequence alignment of the tomato (Solanum lycopersicum) CYP1 (CAA05894) with its papain-like cysteine protease homologs from Arabidopsis thaliana (RD21a, NP_564497), sweet potato (Ipomoea batatas, AAK48495), and potato (Solanum tuberosum, CAB53515.1). Conserved residues of the cysteine protease active site are indicated by black boxes, and gaps introduced for alignment are indicated by dashes. Alignment was performed using the ClustalW algorithm (www.genebee.msu.su/clustal/advanced.html). (B) Interaction in the Y2H system. The indicated cell inocula were plated on a leucine-deficient growth medium. In this assay system, growth in the absence of leucine represents selective conditions for protein-protein interaction. Lane 1, TYLCV V2 – iCYP1; Lane 2, TYLCV V2 – mCYP1; Lane 3, control plasmid pRFHM1.