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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
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Rho small G-protein-dependent binding of mDia to an Src homology 3 domain-containing IRSp53/BAIAP2

T Fujiwara1, A Mammoto, Y Kim

  • 1Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/ Faculty of Medicine, Suita, 565-0871, Japan.

Biochemical and Biophysical Research Communications
|May 18, 2000
PubMed

Insights

The study identifies Insulin Receptor Substrate p53 (IRSp53)/Brain-specific Angiogenesis Inhibitor 1-Associated Protein 2 (BAIAP2) as a binding protein for mDia1. This protein interaction suggests IRSp53/BAIAP2 acts as a downstream effector of mDia1 in cellular processes.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Signal Transduction

Background:

  • mDia1 is a key regulator of the actin cytoskeleton, involved in stress fiber formation and cytokinesis.
  • Rho GTPases are critical regulators of cell shape, motility, and division.
  • IRSp53/BAIAP2 has been identified independently as an insulin-responsive protein and a binding partner for BAI1.

Purpose of the Study:

  • To identify novel binding partners of mDia1.
  • To elucidate the functional relationship between mDia1 and IRSp53/BAIAP2.
  • To investigate the molecular mechanism of mDia1-IRSp53/BAIAP2 interaction.

Main Methods:

  • Protein co-immunoprecipitation to identify mDia1-binding proteins.
  • Yeast two-hybrid assays to confirm protein-protein interactions.
  • In vitro binding assays using purified protein domains.

Main Results:

  • IRSp53/BAIAP2 was identified as a novel mDia1-binding protein.
  • The formin homology 1 (FH1) domain of mDia1 directly interacted with the Src homology 3 (SH3) domain of IRSp53/BAIAP2.
  • This interaction was dependent on GTP-bound Rho, a known activator of mDia1.

Conclusions:

  • IRSp53/BAIAP2 is a downstream effector of mDia1.
  • The interaction between mDia1 and IRSp53/BAIAP2 provides a new link in Rho GTPase signaling pathways.
  • This finding has implications for understanding cytoskeletal regulation and cell division.

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