FIG. 2.

Interaction between P2 and other RTBV proteins in the yeast two-hybrid system. Yeast strain HF7c was cotransformed with a plasmid encoding the Gal4AD-P2 fusion protein and a plasmid expressing one of the other RTBV proteins fused to the Gal4BD (A) or with plasmid pairs encoding the various Gal4 domain-RTBV protein fusions in the opposite combination (B). The β-galactosidase activity produced by the resulting transformants was assessed by filter assay, with the appearance of a blue color indicating interaction between the proteins tested. The strength of the interactions was estimated by the intensity of the blue coloration after 6 h: +++, dark blue; +, light blue; −, no color. The time taken for the blue color to appear is indicated in parentheses.