TABLE 1.

Summary of biochemical activities of various Su(Z)2 and PSC proteins and complexes used this studya

Protein or complexActive fraction (%)Kd for DNA (nM)50% inhibition in REA assays (protein/nuc ratio)b
12 nuc1 nuc
Active concnTotal concnActive concnTotal concnActive concnTotal concn
PSC27.3 ± 2.00.17 ± 0.0462 ± 0.150.51.8>10
Su(Z)227.8 ± 4.11.58 ± 0.215.68 ± 0.760.51.82.59.0
Su(Z)2-N0.8 ± 0.2>50>16
Su(Z)2-C22.5 ± 2.10.17 ± 0.050.76 ± 0.220.73.1
PSC complexc30-500.13 ± 0.080.3
Su(Z)2 complex22.3 ± 1.21.06 ± 0.134.75 ± 0.580.52.2
Su(Z)2-N complex2.2 ± 0.20.21 ± 0.039.47 ± 1.460.2d7.0
Su(Z)2-N ΔPh complex1.5 ± 0.1>500.2d13.0
  • a Values that are in boldface are calculated from data obtained from experiments by adjusting for active fractions.

  • b nuc, nucleosome.

  • c Data were obtained from Francis et al. (16).

  • d Adjustment for the minimally active fractions of the Su(Z)2-N and Su(Z)2-N ΔPh complexes resulted in an affinity for DNA and a 50% inhibition of chromatin remodeling that is similar to those of complexes containing full-length PSC, suggesting that the complex preparations might contain trace amounts of other active proteins.