Figure 4.

Specific interaction of P22 with the HFi22 protein encoded by a N. tabacum cDNA. Yeast L40 cells were cotransformed with either the lamin bait construct (pSTT91/lamin) and HFi22 prey plasmids (sections on top one-half of plates) or the P22 bait plus HFi22 plasmids (bottom one-half of plates). Colonies were grown in the absence of Leu and Trp (L⁻,T⁻; left) as indicators that both bait and prey plasmids were present in the yeast cells, and a β-galactosidase assay (β-gal) was performed to test for protein interaction (middle). No β-galactosidase reaction was observed with colonies transformed only with the P22 bait or HFi22 prey plasmids (not shown). The plate on the right shows colonies grown in absence of Leu, Trp, and His (L⁻,T⁻,H⁻). Compared with the L⁻,T⁻ plate, the colony density on this representative L⁻,T⁻,H⁻ plate is lower but the size of individual colonies is comparable.