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An RNA-binding protein associated with Src through its SH2 and SH3 domains in mitosis

S J Taylor1, D Shalloway

  • 1Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.

Nature
|April 28, 1994
PubMed

Insights

Activated c-Src kinase during mitosis phosphorylates and binds a 68K protein (p68). This suggests c-Src may regulate RNA processing, trafficking, or translation during the cell cycle.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • c-Src tyrosine kinase activity increases during mitosis via dephosphorylation.
  • Mitotic c-Src activation enhances Src homology-2 (SH2) domain binding.
  • Physiological targets of mitotic c-Src remain largely unidentified.

Purpose of the Study:

  • To identify physiological targets of activated c-Src during mitosis.
  • To investigate the interaction between c-Src and its mitotic targets.

Main Methods:

  • Tyrosine phosphorylation assays in mouse fibroblasts during mitosis.
  • Co-immunoprecipitation to detect protein-protein interactions.
  • In vitro binding assays using Src SH2 and SH3 domains.
  • Analysis of p68 protein homology and binding partners.

Main Results:

  • A 68K protein (p68) is tyrosine-phosphorylated and associates with Src during mitosis.
  • p68 binds independently to Src SH2 and SH3 domains in vitro.
  • Both SH2 and SH3 domains are essential for p68 phosphorylation and binding in vivo.
  • p68 shares homology with p62, known to bind polyribonucleotides.

Conclusions:

  • Mitotic c-Src directly interacts with and phosphorylates p68.
  • The interaction involves both SH2 and SH3 domains of c-Src.
  • c-Src may regulate RNA-related processes (processing, trafficking, translation) in a cell-cycle-dependent manner.

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