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The tumor-sensitive calmodulin-like protein is a specific light chain of human unconventional myosin X

M S Rogers1, E E Strehler

  • 1Tumor Biology Program, Department of Biochemistry and Molecular Biology, Mayo Graduate School and Mayo Clinic Cancer Center, Mayo Clinic/Foundation, Rochester, Minnesota 55905, USA.

The Journal of Biological Chemistry
|March 30, 2001
PubMed

Insights

Human calmodulin-like protein (CLP) binds to unconventional myosin X. This interaction, crucial for cell regulation, is calcium-dependent and may be disrupted in cancers lacking CLP.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Human calmodulin-like protein (CLP) is an epithelial-specific calcium-binding protein.
  • CLP expression is significantly reduced in various cancers.
  • CLP regulates cellular functions through calcium-dependent protein interactions, similar to calmodulin.

Purpose of the Study:

  • To identify proteins that interact with human calmodulin-like protein (CLP).
  • To investigate the nature and specificity of the interaction between CLP and its binding partners.
  • To determine the functional implications of CLP-protein interactions in cellular processes.

Main Methods:

  • Gel overlay assays to identify CLP-binding proteins.
  • Yeast two-hybrid screening to identify CLP-interacting partners.
  • Pull-down assays and surface plasmon resonance to confirm direct binding and determine affinity.
  • Immunofluorescence microscopy and co-precipitation assays to assess in vivo interaction and localization.

Main Results:

  • A 210-kDa protein was identified that binds CLP specifically and calcium-dependently.
  • Yeast two-hybrid screening identified unconventional myosin X's IQ motifs as CLP-binding domains.
  • CLP directly binds to the IQ domain of myosin X in a calcium-dependent manner, with high affinity for IQ motif 3.
  • CLP colocalizes with myosin X at the cell periphery and functions as a specific light chain for myosin X in vivo.

Conclusions:

  • CLP specifically binds to unconventional myosin X, acting as its light chain.
  • Myosin X is a likely in vivo target for CLP-mediated regulation.
  • Dysregulation of myosin X by CLP loss in cancer may impact cell motility, signaling, and growth.

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