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Updated: Jul 10, 2026

Pull-down of Calmodulin-binding Proteins
07:51

Pull-down of Calmodulin-binding Proteins

Published on: January 23, 2012

Ca2+-dependent calmodulin binding to FcRn affects immunoglobulin G transport in the transcytotic pathway

Bonny L Dickinson1, Steven M Claypool, June A D'Angelo

  • 1The Research Institute for Children, Children's Hospital, Department of Pediatrics, New Orleans, LA 70118, USA.

Molecular Biology of the Cell
|November 16, 2007
PubMed

Insights

Calmodulin binding to the Fc neonatal receptor (FcRn) regulates immunoglobulin G (IgG) transport. This interaction directs FcRn and IgG away from degradation and into a bidirectional pathway, impacting mucosal immunity.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Biology

Background:

  • The Fc gamma receptor, FcRn, is crucial for immunoglobulin G (IgG) transport.
  • FcRn prevents IgG degradation and facilitates its movement across epithelial barriers, influencing mucosal immunity.

Purpose of the Study:

  • To identify regulatory mechanisms of FcRn trafficking and IgG transport.
  • To investigate the role of the FcRn cytoplasmic tail in FcRn function.

Main Methods:

  • Identification of a calmodulin-binding site in the FcRn cytoplasmic tail.
  • Analysis of FcRn mutants with altered cytoplasmic tail motifs.
  • Assessment of FcRn half-life and transcytosis.
  • Use of chemical calmodulin inhibitors.

Main Results:

  • A direct, calcium-dependent calmodulin-binding site was identified in the FcRn cytoplasmic tail.
  • FcRn mutants lacking this site or the entire tail showed reduced half-life and impaired transcytosis.
  • Calmodulin inhibition mimicked the mutant FcRn phenotype, reducing IgG transcytosis.

Conclusions:

  • Calmodulin binding to FcRn is a novel regulatory mechanism for IgG transport.
  • This interaction promotes FcRn sorting into a bidirectional transcytotic pathway, avoiding degradation.
  • The findings provide new insights into FcRn-mediated mucosal immunity.

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