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Phosphorylation sites in the amino-terminal region of mouse p53

Y Wang1, W Eckhart

  • 1Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92186.

Proceedings of the National Academy of Sciences of the United States of America
|May 15, 1992
PubMed

Insights

This study identifies key in vivo phosphorylation sites in the N-terminal region of mouse p53, specifically serines 7, 9, 18, and 37. These findings advance understanding of p53 regulation through protein phosphorylation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Phosphorylation is a critical post-translational modification regulating protein function.
  • The tumor suppressor p53 is a key target for regulatory phosphorylation.
  • Previous studies identified in vitro phosphorylation sites on p53 by various kinases.

Purpose of the Study:

  • To identify in vivo phosphorylation sites in the amino-terminal region of mouse p53.
  • To investigate the role of double-stranded DNA-dependent kinase (DNA-PK) in p53 phosphorylation.
  • To characterize the phosphorylation pattern of p53 in a cellular context.

Main Methods:

  • Site-directed mutagenesis of potential serine phosphorylation sites in mouse p53.
  • Analysis of mutant p53 proteins using tryptic phosphopeptide mapping.
  • In vitro phosphorylation assays using purified mouse p53 and DNA-PK.

Main Results:

  • Identified serine-7, -9, -18, and -37 as in vivo phosphorylation sites in mouse p53's amino-terminal region.
  • Demonstrated that DNA-PK phosphorylates mouse p53 on these N-terminal serine residues in vitro.
  • Confirmed that casein kinase II and p34cdc2 kinase phosphorylate p53 at distinct sites (serine-389 and serine-315, respectively) in vitro.

Conclusions:

  • The amino-terminal region of mouse p53 contains multiple in vivo phosphorylation sites.
  • DNA-PK is a significant kinase involved in the in vivo phosphorylation of mouse p53.
  • Understanding these phosphorylation events is crucial for elucidating p53's regulatory mechanisms and its role in cellular processes.

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