FIG. 2.

EMSA with purified C1 protein. The restriction endonuclease PvuII was used to cleave the P1 EcoRI-19 DNA fragment into two subfragments of 644 and 399 bp. The smaller DNA fragment contained the Op2b putative binding site for the C1 repressor protein. A constant amount of DNA (2 μg per reaction) was incubated with increasing amounts of C1 protein in a total reaction volume of 20 μl. A standard size marker with fragment sizes indicated in base pairs was loaded on the left side of the gel.