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Updated: Jun 6, 2026

Pull-down of Calmodulin-binding Proteins
07:51

Pull-down of Calmodulin-binding Proteins

Published on: January 23, 2012

Global dynamic conformational changes in the suppressor domain of IP3 receptor by stepwise binding of the two lobes

Sunmi Kang1, Hyuknam Kwon, He Wen

  • 1Department of Biochemistry and Center for Advanced Medical Education by BK21 Project, School of Medicine, Inha University, Chungsuk Bldg., Rm. 505, Shinheung-dong, Chung-gu, Incheon, Korea, 400-712.

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology
|November 19, 2010
PubMed

Insights

Calmodulin (CaM) binding to the inositol-1,4,5-trisphosphate receptor (IP3R) suppressor domain causes unfolding and conformational changes, revealing a novel mechanism for calcium/CaM inhibition of IP3R.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Signaling

Background:

  • The precise role of calmodulin (CaM) in regulating the inositol-1,4,5-trisphosphate receptor (IP3R) remains a subject of debate.
  • Understanding CaM's interaction with the IP3R suppressor domain is crucial for elucidating IP3R regulation.

Purpose of the Study:

  • To investigate the interaction between calmodulin and the suppressor domain of the inositol-1,4,5-trisphosphate receptor.
  • To elucidate the structural and dynamic mechanisms underlying CaM-mediated regulation of IP3R.

Main Methods:

  • Pulldown assays and fluorescence titration experiments to confirm CaM-IP3R suppressor domain interaction.
  • Nuclear Magnetic Resonance (NMR) spectroscopy to analyze conformational changes induced by CaM binding.
  • Utilized CaM deletion mutants to assess the role of individual CaM lobes.

Main Results:

  • Confirmed direct interaction between CaM and the IP3R suppressor domain.
  • Demonstrated that apo-CaM induces significant dynamic conformational changes, including partial unfolding, in the IP3R suppressor domain.
  • Showed that the C-lobe of CaM alone can induce these changes, while calcium binding facilitates N-lobe interaction, leading to further conformational alterations in both proteins.

Conclusions:

  • Proposed a novel model for calcium/CaM inhibition of IP3R involving partial unfolding of the suppressor domain by apo-CaM and stepwise N-lobe binding.
  • This mechanism provides new insights into CaM-target interactions and reconciles previous findings on IP3R regulation.

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