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Ca2+/CaM-dependent inactivation of the skeletal muscle L-type Ca2+ channel (Cav1.1)

Katarina Stroffekova1

  • 1Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA. stroffek@biology.usu.edu

Pflugers Archiv : European Journal of Physiology
|September 28, 2007
PubMed

Insights

Calmodulin (CaM) binds to and regulates the skeletal muscle L-type calcium channel (Cav1.1). This Ca2+-dependent modulation is crucial for Cav1.1 channel function in muscle cells.

Area of Science:

  • Biophysics
  • Molecular Biology
  • Muscle Physiology

Background:

  • Calmodulin (CaM) is known to modulate many high-voltage-activated Ca2+ channels.
  • The interaction between CaM and the skeletal muscle L-type Ca2+ channel (Cav1.1) has not been previously investigated.

Purpose of the Study:

  • To determine if Ca2+-dependent modulation by CaM affects Cav1.1 channel function.
  • To investigate the direct association between Cav1.1 and CaM in skeletal muscle cells.

Main Methods:

  • Whole-cell patch-clamp recordings in cultured mouse myotubes.
  • Fluorescent resonance energy transfer (FRET) to detect protein-protein interactions.
  • Overexpression of wild-type and mutant calmodulin in myotubes.

Main Results:

  • Cav1.1 currents exhibited Ca2+-dependent inactivation (CDI) with typical characteristics.
  • CDI was significantly reduced in myotubes overexpressing a Ca2+-uncoupled CaM mutant.
  • FRET analysis confirmed a direct association between Cav1.1 and CaM in vivo.

Conclusions:

  • Calmodulin directly associates with the Cav1.1 channel.
  • Calmodulin binding mediates Ca2+-dependent modulation of Cav1.1 channel activity.
  • This interaction is important for skeletal muscle function.

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