Phosphorylation sites in the amino-terminal region of mouse p53.
Phosphorylation is an attractive mechanism for regulating the functions of p53. The p34cdc2 kinase, which is involved in regulation of the cell cycle, phosphorylates serine-315 of human p53 in vitro. Casein kinase II phosphorylates serine-389 of mouse p53 in vitro. The amino-terminal region of mouse p53 contains a cluster of potential serine phosphorylation sites. Those sites have been proposed to be sites for phosphorylation by a double-stranded DNA-dependent kinase (DNA-PK) from HeLa cells and can be dephosphorylated by protein phosphatase 2A. To identify in vivo phosphorylation sites in the amino-terminal region of mouse p53, we mutated potential phosphorylation sites and analyzed the mutant proteins by tryptic phosphopeptide mapping. We identified serine-7, -9, -18, and -37 as in vivo phosphorylation sites. We further showed that mouse p53 expressed in bacteria is phosphorylated by DNA-PK on amino-terminal serine residues in vitro.
Wang
Y
Y
Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92186.
Eckhart
W
W
D000595:Amino Acid Sequence; D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010710:Phosphates / Q000378:metabolism*; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D012694:Serine; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D010710:Phosphates; D010748:Phosphopeptides; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D012694:Serine; D016203:CDC2 Protein Kinase