Related Experiment Video

Updated: May 9, 2025

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion
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Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion

Published on: June 15, 2019

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Structure of the complex of C1q-like 3 protein with adhesion-GPCR BAI3

Yi Miao1,2,3, Haoqing Wang4, Kevin M Jude5,6,7

  • 1Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA. yimiao@ust.hk.

Communications Biology
|May 2, 2025
PubMed

Insights

Researchers elucidated the molecular basis of how Brain-specific Angiogenesis Inhibitor-3 (BAI3) binds to C1q-like proteins (C1qls) using cryo-EM. This reveals a novel hexameric complex crucial for synaptic organization in the brain.

Area of Science:

  • Neuroscience
  • Structural Biology
  • Molecular Biology

Background:

  • The adhesion-GPCR BAI3 is vital for synaptic organization.
  • The interaction between BAI3 and its ligand C1qls is not well understood.

Purpose of the Study:

  • To determine the structural basis of the C1ql3-BAI3 complex formation.
  • To elucidate the molecular mechanisms underlying BAI3-mediated synaptic organization.

Main Methods:

  • Single-particle cryo-electron microscopy (cryo-EM) at 2.8 Å resolution.
  • Mutant analysis.
  • Cell surface staining.

Main Results:

  • Determined the cryo-EM structure of the C1ql3-BAI3 complex, revealing a hexameric assembly.
  • C1ql3 forms a homotrimer that binds three BAI3 molecules in its inter-domain grooves.
  • Identified calcium ion-mediated interactions distinct from other C1q-like domain complexes.
  • Mutant analysis confirmed key residues involved in the interaction.

Conclusions:

  • The study reveals a unique hexameric binding mechanism between C1ql3 and BAI3.
  • This structural insight enhances understanding of C1ql-BAI3-mediated synaptic organization.
  • The findings shed light on the functional dynamics of BAI3 in neural synapses.

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