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Updated: Jul 7, 2026

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Isoform-specific inhibition of TRPC4 channel by phosphatidylinositol 4,5-bisphosphate

Ken-ichi Otsuguro1, Jisen Tang, Yufang Tang

  • 1Cardiovascular Biomedical Research Centre, School of Medicine and Dentistry, Queen's University Belfast, Belfast, United Kingdom.

The Journal of Biological Chemistry
|January 31, 2008
PubMed

Insights

Phosphatidylinositol 4,5-bisphosphate (PIP(2)) selectively inhibits the TRPC4alpha channel, not TRPC4beta. PIP(2) breakdown and G(i/o) protein activation are crucial for TRPC4alpha channel function.

Area of Science:

  • Molecular Biology
  • Cell Physiology
  • Biochemistry

Background:

  • Transient receptor potential (TRP) channels, including TRPC4alpha and TRPC4beta, regulate membrane potential and calcium (Ca2+) influx in smooth muscle and endothelial cells.
  • TRPC4 channels are activated by Gq/phospholipase C-coupled receptors, but the precise activation mechanism and isoform-specific regulation are not fully understood.

Purpose of the Study:

  • To investigate the role of phosphatidylinositol 4,5-bisphosphate (PIP(2)) in regulating TRPC4alpha and TRPC4beta channel activity.
  • To elucidate the mechanism of PIP(2) inhibition and its dependence on channel structure and cellular components.

Main Methods:

  • In vitro binding assays to assess PIP(2) interaction with TRPC4 isoforms.
  • Electrophysiological recordings to measure channel activity in the presence of various phosphoinositides and inhibitors.
  • Experiments involving cytochalasin D and deletion mutants to examine the role of the actin cytoskeleton.

Main Results:

  • TRPC4alpha, but not TRPC4beta, was strongly inhibited by intracellular PIP(2).
  • PIP(2) binds selectively to the C terminus of TRPC4alpha, and its inhibitory effect depends on the association with the actin cytoskeleton via a PDZ-binding motif.
  • PIP(2) breakdown, along with Ca2+ and pertussis toxin-sensitive G(i/o) proteins, is required for TRPC4alpha channel activation.

Conclusions:

  • TRPC4alpha activity is tightly regulated by intracellular PIP(2) in a manner dependent on its C-terminal PDZ-binding motif and interaction with the actin cytoskeleton.
  • TRPC4 channels integrate diverse G-protein-dependent signals, including PIP(2)/cytoskeleton interactions, suggesting a complex regulatory network.

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