Identification of a CK2 phosphorylation site in mdm2.
Mdm2 is a cellular oncoprotein the most obvious function of which is the down-regulation of the growth suppressor protein p53. It represents a highly phosphorylated protein but only little is yet known about the sites phosphorylated in vivo, the kinases that are responsible for the phosphorylation or the functional relevance of the phosphorylation status. Recently, we have shown that mdm2 is a good substrate for protein kinase CK2 at least in vitro. Computer analysis of the primary amino acid sequence of mdm2 revealed 19 putative CK2 phosphorylation sites. By using deletion mutants of mdm2 and a peptide library we identified the serine residue at position 269 which lies within a canonical CK2 consensus sequence (EGQELSDEDDE) as the most important CK2 phosphorylation site. Moreover, by using the mdm2 S269A mutant for in vitro phosphorylation assays this site was shown to be phosphorylated by CK2. Binding studies revealed that phosphorylation of mdm2 at S269 does not have any influence on the binding of p53 to mdm2.
Götz
C
C
Department of Medical Biochemistry and Molecular Biology, University of the Saarland, Homburg, Germany. bccgoe@med-rz-uni-sb.de
Kartarius
S
S
Scholtes
P
P
Nastainczyk
W
W
Montenarh
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D047390:Casein Kinase II; D002460:Cell Line; D003062:Codon; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007313:Insecta; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D003062:Codon; D009687:Nuclear Proteins; D010455:Peptides; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases