DNA-activated protein kinase in Raji Burkitt's lymphoma cells. Phosphorylation of c-Myc oncoprotein.
Autophosphorylation of a DNA-activated protein kinase (DNA-PK) in Raji Burkitt's lymphoma cells generated a band that corresponded to a phosphoprotein of about 300 kDa on SDS/PAGE. This band corresponds to a 300-350-kDa DNA-PK found previously in HeLa cells. In addition to the 300-kDa phosphoprotein, the band of a highly phosphorylated 58-kDa protein was detected by SDS/PAGE of partially purified DNA-PK preparations after the phosphorylation reaction in the presence of double-stranded DNA. This phosphoprotein was specifically immunoprecipitated by phosphoprotein nor detectable activities of other kinases, phosphorylated recombinant c-Myc proteins in the presence of DNA. The c-Myc phosphorylation by DNA-PK was markedly stimulated by relaxed, double-stranded DNA, but neither by single-stranded DNA nor by RNA. Phosphopeptide mapping and phosphoamino acid analysis indicated that DNA-PK phosphorylates c-Myc in vitro at several serine residues.
Iijima
S
S
Department of Pathological Biochemistry, Tokyo Medical and Dental University, Japan.
Teraoka
H
H
Date
T
T
Tsukada
K
K
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002051:Burkitt Lymphoma; D002848:Chromatography, DEAE-Cellulose; D004247:DNA / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D009842:Oligopeptides; D016271:Proto-Oncogene Proteins c-myc; D011994:Recombinant Proteins; D004247:DNA; D011494:Protein Kinases