FIG. 4.

Interaction of C17 with wild-type or mutant TFIIIB70 proteins. The two-hybrid system was used to investigate protein-protein interactions between C17 and TFIIIB70. The ORF of C17 was fused in frame with the GAL4 DNA-binding domain (amino acids 1 to 147). Wild-type or mutant TFIIIB70 ORF was fused in frame with the GAL4 activation domain (amino acids 768 to 881). Numbers in parentheses indicate the TFIIIB70 amino acids present in the fusion protein. TFIIIB70 motifs homologous to TFIIB are indicated. Transcription activation of the lacZ reporter gene was assayed by growing the transformed cells on selective medium and overlaying with 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside (X-Gal) agar. White (−) and blue (+) coloration of cell patches on X-Gal plates is indicated.