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A novel RalGEF-like protein, RGL3, as a candidate effector for rit and Ras

H Shao1, D A Andres

  • 1Department of Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0230, USA.

The Journal of Biological Chemistry
|June 28, 2000
PubMed

Insights

Researchers identified RGL3, a novel protein interacting with Rit and Ras small GTPases. RGL3 acts as a guanine nucleotide exchange factor for Ral, suggesting it

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Oncogenesis

Background:

  • The small GTPase Rit, a Ras relative, can induce oncogenic transformation.
  • Rit's effector loop is similar to Ras, but it interacts with different effector proteins.
  • Novel cellular targets are likely responsible for Rit's transforming activity.

Purpose of the Study:

  • To identify Rit-binding proteins and understand Rit's cellular function.
  • To investigate potential novel downstream effectors for Rit.

Main Methods:

  • Yeast two-hybrid screening was employed to identify Rit-binding proteins.
  • Interaction studies focused on the C-terminal Rit/Ras interaction domain of RGL3.
  • Guanine nucleotide exchange activity of RGL3 toward Ral was assessed.

Main Results:

  • RGL3 (Ral GEF-like 3) was identified as a Rit-binding protein.
  • RGL3 shares sequence identity with known Ral guanine nucleotide exchange factors (RalGEFs).
  • RGL3 interacts with Rit and Ras in a GTP- and effector loop-dependent manner.
  • RGL3 exhibits guanine nucleotide exchange activity toward Ral, stimulated by activated Rit or Ras.

Conclusions:

  • RGL3 functions as a guanine nucleotide exchange factor for the small GTPase Ral.
  • RGL3 may act as a downstream effector for both Rit and Ras signaling pathways.
  • These findings provide insight into the novel mechanisms of Rit-mediated oncogenesis.

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