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pp125FAK a structurally distinctive protein-tyrosine kinase associated with focal adhesions

M D Schaller1, C A Borgman, B S Cobb

  • 1Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908.

Proceedings of the National Academy of Sciences of the United States of America
|June 1, 1992
PubMed

Insights

Researchers identified a novel protein-tyrosine kinase, pp125, in chicken cells. This protein, now named focal adhesion kinase, is crucial for cell growth regulation and becomes more phosphorylated upon Rous sarcoma virus transformation.

Area of Science:

  • Cell Biology
  • Oncology
  • Biochemistry

Background:

  • Rous sarcoma virus oncoprotein pp60v-src disrupts normal cell growth, leading to oncogenic transformation.
  • This transformation is linked to increased tyrosine phosphorylation of cellular proteins by pp60v-src.

Purpose of the Study:

  • To identify and characterize cellular proteins whose tyrosine phosphorylation is altered by pp60v-src.
  • To isolate and study the cDNA encoding a major phosphotyrosine-containing protein in chicken embryo cells.

Main Methods:

  • cDNA isolation and sequencing.
  • Protein expression analysis.
  • Immunofluorescence localization.

Main Results:

  • A cDNA encoding a protein, pp125, was isolated. pp125 is a major phosphotyrosine-containing protein in untransformed cells and shows increased phosphotyrosine in transformed cells.
  • pp125 is a cytoplasmic protein-tyrosine kinase, potentially representing a new family of such kinases.
  • Immunofluorescence revealed pp125 localizes to focal adhesions.

Conclusions:

  • pp125 is identified as focal adhesion kinase (FAK).
  • FAK is a novel cytoplasmic protein-tyrosine kinase and a major phosphotyrosine-containing protein.
  • FAK's localization to focal adhesions suggests a role in cell adhesion and signaling pathways relevant to oncogenic transformation.

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