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Biochemical and Structural Studies of the Interaction between ARAP1 and CIN85

Qingxia Li1, Wanfa Yang, Yue Wang1

  • 1Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute , Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center , Shenzhen 518036 , China.

Biochemistry
|March 29, 2018
PubMed

Insights

Arf-GAP with Rho-GAP domain, ANK repeat and PH domain-containing protein 1 (ARAP1) binds specifically to Cbl-interacting protein of 85 kDa (CIN85) via its SH3B domain. This interaction regulates epidermal growth factor receptor (EGFR) internalization by competing with Cbl binding.

Area of Science:

  • Cellular Biology
  • Molecular Mechanisms
  • Protein Interactions

Background:

  • Epidermal growth factor receptor (EGFR) internalization and recycling are crucial cellular processes.
  • ARAP1, CIN85, and Cbl are key regulators of EGFR trafficking.
  • Previous studies indicated ARAP1-CIN85 interaction affects EGFR ubiquitination, but the mechanism remained elusive.

Purpose of the Study:

  • To elucidate the molecular mechanism of ARAP1-CIN85 interaction.
  • To characterize the binding affinity and specificity between ARAP1 and CIN85.
  • To understand how ARAP1 regulates CIN85-mediated EGFR internalization.

Main Methods:

  • Biochemical and structural characterization of ARAP1-CIN85 interaction.
  • Analysis of binding motifs and critical interaction residues.
  • Protein swapping experiments and structure alignment.
  • Competitive analytical gel-filtration chromatography and isothermal titration calorimetry (ITC).

Main Results:

  • The CIN85 SH3B domain binds the ARAP1 PXPXXRX(XXR/H/K) motif with high affinity and specificity.
  • The β2-β3 loops of CIN85 SH3 domains and specific residue interactions (H87ARAP1/E132CIN85) are critical for binding specificity.
  • ARAP1 competes with Cbl for binding to CIN85.

Conclusions:

  • ARAP1 binds CIN85 through a specific motif and interaction interface.
  • ARAP1's competition with Cbl for CIN85 binding provides a mechanism for regulating EGFR internalization.
  • This study offers a biochemical basis for ARAP1's role in CIN85-mediated EGFR trafficking.

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