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Src-dependent tyrosine phosphorylation regulates dynamin self-assembly and ligand-induced endocytosis of the

Seungkirl Ahn1, Jihee Kim, Carmen L Lucaveche

  • 1Howard Hughes Medical Institute, Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.

The Journal of Biological Chemistry
|May 16, 2002
PubMed

Insights

Phosphorylation of dynamin I by c-Src kinase triggers its self-assembly and enhances GTPase activity, crucial for receptor internalization. This tyrosine phosphorylation at residue 597 is essential for the endocytosis process.

Area of Science:

  • Cell biology
  • Molecular biology
  • Biochemistry

Background:

  • Endocytosis of activated receptors relies on dynamin-mediated GTP hydrolysis.
  • Dynamin self-assembly is a key regulatory mechanism for this process.

Purpose of the Study:

  • To investigate the role of c-Src kinase in regulating dynamin I function.
  • To elucidate the mechanism by which c-Src influences dynamin I self-assembly and GTPase activity.

Main Methods:

  • In vitro phosphorylation assays using c-Src kinase.
  • Electron microscopy to visualize dynamin I self-assembly.
  • Site-directed mutagenesis (Y597F) to assess the role of tyrosine 597.
  • Cellular expression studies to evaluate receptor internalization.

Main Results:

  • Phosphorylation of dynamin I by c-Src induces its self-assembly into ring stacks and increases GTPase activity.
  • Tyrosine 597 was identified as the specific phosphorylation site by c-Src.
  • Mutation of tyrosine 597 to phenylalanine abrogated c-Src-induced self-assembly and GTPase activity.
  • Expression of the Y597F mutant dynamin I impaired epidermal growth factor receptor internalization.

Conclusions:

  • c-Src-mediated tyrosine phosphorylation of dynamin I at residue 597 is essential for its self-assembly and GTPase activity.
  • This phosphorylation event is critical for the proper function of dynamin in ligand-induced receptor internalization.

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