Identification of elongation factor-1alpha as a Ca2+/calmodulin-binding protein in Tetrahymena cilia

Cell Motil Cytoskeleton. 2003 May;55(1):51-60. doi: 10.1002/cm.10111.

Abstract

Calmodulin (CaM) is known to be a ciliary component. However, the function of CaM in cilia or flagella has not been well understood. Immunoelectron microscopy using anti-CaM antibody showed that CaM was localized on the axonemal microtubules (MTs) and matrix of Tetrahymena cilia. To investigate the signal transduction of Ca(2+)/CaM in cilia, we performed Ca(2+)/CaM-affinity column chromatography in the membrane and matrix fraction. Elongation factor-1alpha (EF-1alpha) was identified as a Ca(2+)/CaM-binding protein in cilia. EF-1alpha is a highly conserved protein and functions in protein translation. In addition, EF-1alpha has been reported to interact with MTs and F-actin in several organisms. Immunoelectron microscopy showed that EF-1alpha was localized on the axonemal MTs. However, in immunoblot analysis, EF-1alpha was mainly extracted in the membrane and matrix fraction from the axonemal MTs by 1% Triton X-100 extraction. These results suggest that interaction between EF-1alpha and axonemal MTs is weak and sensitive to treatment with 1% Triton X-100 and that EF-1alpha mediates between axonemal MTs and CaM in the presence of Ca(2+). Moreover, EF-1alpha was also localized in cilia of Paramecium, suggesting that EF-1alpha functions as a target protein of Ca(2+)/CaM in ciliate cilia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Calmodulin / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Cilia / drug effects
  • Cilia / metabolism*
  • Cilia / ultrastructure
  • Immunohistochemistry
  • Microscopy, Electron
  • Microtubules / drug effects
  • Microtubules / metabolism
  • Microtubules / ultrastructure
  • Paramecium / metabolism
  • Paramecium / ultrastructure
  • Peptide Elongation Factor 1 / metabolism*
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Tetrahymena thermophila / growth & development*
  • Tetrahymena thermophila / metabolism*
  • Tetrahymena thermophila / ultrastructure

Substances

  • Calmodulin
  • Peptide Elongation Factor 1
  • Calcium