Identification of elongation factor-1alpha as a Ca2+/calmodulin-binding protein in Tetrahymena cilia.
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.
Ueno
Hironori
H
Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Gonda
Kohsuke
K
Takeda
Tetsuya
T
Numata
Osamu
O
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002147:Calmodulin / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002923:Cilia / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010247:Paramecium / Q000378:metabolism / Q000648:ultrastructure; D020648:Peptide Elongation Factor 1 / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D016808:Tetrahymena thermophila / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure
D002147:Calmodulin; D020648:Peptide Elongation Factor 1; D002118:Calcium