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Updated: Jun 21, 2026

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The structural basis of Arf effector specificity: the crystal structure of ARF6 in a complex with JIP4

Tatiana Isabet1, Guillaume Montagnac, Karine Regazzoni

  • 1Institut Curie, Centre de Recherche, Paris, France.

The EMBO Journal
|August 1, 2009
PubMed

Insights

JNK-interacting proteins (JIPs) specifically bind to ARF6-GTP, regulating motor protein attachment. Structural analysis reveals key residues driving JIP4 specificity for ARF6, clarifying ARF6-mediated motor regulation.

Area of Science:

  • Molecular biology
  • Structural biology
  • Cellular signaling

Background:

  • JNK-interacting proteins (JIP3 and JIP4) are effectors of the small GTP-binding protein ARF6.
  • ARF6-GTP binding to JIP3/JIP4's leucine zipper domains controls JIPs' interaction with kinesin-1 and dynactin.

Purpose of the Study:

  • Determine the crystal structure of ARF6-GTP bound to JIP4's leucine zipper domain (LZII).
  • Elucidate the structural basis for JIP4's specificity towards ARF6.
  • Model the ARF6-JIP complex's membrane association to understand ARF6-mediated motor regulation.

Main Methods:

  • X-ray crystallography at 1.9 A resolution.
  • Site-directed mutagenesis.
  • Surface plasmon resonance (SPR).
  • Structure-derived modeling.

Main Results:

  • The crystal structure revealed a heterotetrameric complex of ARF6-GTP and JIP4-LZII with dyad symmetry (ARF6-(JIP4)2-ARF6).
  • Comparison with ARF1 identified non-conserved residues at the switch region borders as critical for JIP4 specificity.
  • Modeling suggests the JIP4-LZII coiled-coil lies along the membrane, enabling a heterotrimeric complex (one ARF6 bound) for motor regulation.

Conclusions:

  • The study provides the structural basis for JIP4 specificity to ARF6.
  • Identified key residues governing this interaction through mutagenesis and SPR.
  • Offers insights into ARF6-mediated motor switch regulation at the membrane interface.

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