FIG. 2.

Vpr interacts specifically with the product of c2.10 in the yeast two-hybrid system. The L40 reporter strain, cotransformed with LexA and the Gal4 activation domain (GalAD) or GalAD-c2.10 fusion protein, was assayed for histidine prototrophy and β-galactosidase activity. Filter lift assays were used to detect β-galactosidase activity. LexA fusions are Vpr amino acids 12 to 96, Daughterless protein of Drosophila (Da), and retinoblastoma (Rb). Growth in the absence of histidine and a high level of β-galactosidase activity (represented by a strong blue color of the colony) are indications of an interaction between the hybrid proteins. The results obtained with two individual transformants are shown for each transformation.