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Investigation of factors that influence phosphorylation of pp60c-src on tyrosine 527

S M Schuh1, J S Brugge

  • 1Department of Microbiology, State University of New York, Stony Brook 11794.

Molecular and Cellular Biology
|June 1, 1988
PubMed

Insights

Proto-oncogene pp60c-src phosphorylation at tyrosine 527 is not dependent on membrane association or its own enzymatic activity. These findings suggest a distinct cellular tyrosine kinase mediates this crucial phosphorylation event.

Area of Science:

  • Molecular Biology
  • Oncology
  • Biochemistry

Background:

  • Proto-oncogene pp60c-src is a key regulator of cell signaling.
  • Phosphorylation at tyrosine 527 is known to decrease pp60c-src tyrosine kinase activity.

Purpose of the Study:

  • To investigate factors influencing pp60c-src phosphorylation at tyrosine 527.
  • To determine if membrane association or enzymatic activity affects tyrosine 527 phosphorylation.
  • To identify the kinase responsible for tyrosine 527 phosphorylation.

Main Methods:

  • Creation of mutant pp60c-src variants, including elimination of N-terminal myristylation and enzymatic activity.
  • Analysis of tyrosine 527 phosphorylation in these mutant proteins.
  • In vitro phosphorylation assays using detergent-permeabilized cells.

Main Results:

  • Stable membrane association is not required for tyrosine 527 phosphorylation.
  • Mutational elimination of pp60c-src enzymatic activity did not affect tyrosine 527 phosphorylation efficiency.
  • Conditions were established for efficient in vitro phosphorylation of tyrosine 527.

Conclusions:

  • pp60c-src phosphorylation at tyrosine 527 is independent of its membrane localization and kinase activity.
  • These results support the hypothesis that a cellular tyrosine kinase distinct from pp60c-src mediates phosphorylation at tyrosine 527.
  • The study provides a foundation for further investigation into the specific kinase involved and the regulatory mechanisms of pp60c-src.

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