FIG. 5.

DNA binding with multiprotein complexes of DDB2. The three indicated complexes known to contain DDB2 were used in an electrophoretic mobility shift assay. The reaction mixtures contained a 50-bp duplex with a (6-4) photoproduct (0.1 nM) and COP9 (0.2, 0.4, and 0.8 nM), UV-DDB (0.1, 0.2, and 0.4 nM), and CUL4A (1.1, 2.2, and 4.4 nM) as indicated. These concentrations are expressed relative to the limiting subunit in each complex. UV-DDB contains stoichiometric amounts of DDB1 and DDB2, whereas CUL4A, purified by CUL4A immunoaffinity resin, contains about 3-fold more DDB1 than DDB2, and COP9, purified by DDB2 immunoaffinity resin, contains about 10-fold more DDB2 than DDB1. F, free DNA; B1, UV-DDB-DNA complex; B1*, two UV-DDB-DNA complexes per DNA molecule.