DNA-Dependent Protein Kinase (DNA-PK) Peptide Substrate is a highly specific substrate for DNA-PK, with the sequence Glu-Pro-Pro-Leu-Ser-Gln-Glu-Ala-Phe-Ala-Asp-Leu-Trp-Lys-Lys. The K(m) value for this peptide is 760uM. DNA-PK is a nuclear serine/threonine protein kinase that, when activated by DNA, phosphorylates several DNA-binding substrates, including the tumor suppressor protein p53, the simian virus 40 (SV40) large T antigen and several transcription factors (e.g., SP1, OCT-1, c-Fos and serum response factor).|