FIG. 6.
SET domain point mutants in Set2 are partially defective in transcriptional repression when tethered to a heterologous promoter. (A) The wild-type S. cerevisiae strain YMH171 was transformed with either LexA vector-only, Rpd3-LexA, Set2(WT)-LexA, Set2(R195G)-LexA, or Set2(C201A)-LexA along with the CYC1-lexAop-lacZ reporter plasmid (pCK30), and β-galactosidase assays were performed. Three independent transformants of each strain were assayed in duplicate, and the results are reported as the fold repression relative to the activity of the LexA vector alone. Asterisks indicate that the repression mediated by the two SET domain mutants of Set2 was significantly less (P ≤ 0.05) than that mediated by wild-type Set2-LexA. (B) To monitor expression of the LexA constructs, extracts from the above experiment were immunoblotted with an anti-LexA polyclonal antiserum. Expression of the vector-only LexA DNA-binding domain (which is 24.5 kDa) was omitted from the figure.