Table 1.

DNA-PK kinase activity as a function of monovalent salt in the absence of Ku

ConditionaPhosphorylated peptide (total counts)bFold increase over control counts
16.2 × 1031
221 × 1063,416
36.4 × 1061,032
41.6 × 106258
  • a Reactions with DNA-PK in the absence of Ku were performed as detailed in Materials and Methods, with the following variations: condition 1, 200 μM mutant p53 peptide in place of the wild-type p53 peptide and in 50 mM NaCl; condition 2, 200 μM wild-type p53 peptide and in 50 mM NaCl; condition 3, 200 μM wild-type p53 peptide and in 100 mM NaCl; condition 4, 200 μM wild-type p53 peptide and in 150 mM NaCl. All reactions were done at an ATP concentration of 3.3 × 10−7 M.

  • b PhosphorImager counts of the labeled peptide after separation on an SDS–15 to 20% polyacrylamide gel.