Open AccessDNA‐activated protein kinase in Raji Burkitt's lymphoma cells
Author(s) -
IIJIMA Shigeyuki,
TERAOKA Hirobumi,
DATE Takayasu,
TSUKADA Kinji
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb16964.x
Subject(s) - raji cell , burkitt's lymphoma , cancer research , protein kinase a , dna , lymphoma , chemistry , microbiology and biotechnology , kinase , biology , biochemistry , immunology
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 mAb against c‐Myc. More highly purfied preparations of DNA‐PK, containing neither a 58‐kDa 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 relxed, 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.