Journal Article

F-Actin Bundling Activity of <i>Tetrahymena</i> Elongation Factor lα Is Regulated by Ca<sup>2+</sup>/Calmodulin

Yasuhiro Kurasawa, Kazuko Hanyu, Yoshio Watanabe and Osamu Numata

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 119, issue 4, pages 791-798
Published in print April 1996 | ISSN: 0021-924X
Published online April 1996 | e-ISSN: 1756-2651 | DOI:
F-Actin Bundling Activity of Tetrahymena Elongation Factor lα Is Regulated by Ca2+/Calmodulin

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Translation elongation factor la (EF-la) catalyzes the GTP-dependent binding of amino-acyl-tRNA to the ribosome.Previously, Tetrahymena 14-nm filament-associated protein was identified as EF-la [Kurasawa et aL (1992) Exp. Cell Res; 203, 261–268]. This and several other studies suggest that EF-la functions not only in translation but also in regulation of some part of the cytoskeleton. Tetrahymena EF-lα bound to F-actin and induced bundling of F-actin. We investigated the effects of GTP/GDP and Ca2+calmodulin on F-actin bundling activity of EF-lα. The presence of GTP, GDP, or guanylyl-imidodi-phosphate (GMP-PNP) slightly decreased the amount of EF-lαbound to F-actin, but each had virtually no effect on the F-actin bundling activity. The formation of F-actin bundles by EF-lα was Ca2+-insensitive. In the absence of Ca2+, calmodulin did not bind to EF-lα and F-actin. On the other hand, in the presence of Ca2+, calmodulin directly bound to EF-lα but did not have any serious influence on EF-lα/F-actin binding. Under the conditions, electron microscopy demonstrated that Ca2+/calmodulin completely inhibited the F-actin bundling by EF-lα. These results indicate that Ca2+/calmodulin regulates the F-actin bundling activity of EF-lα without inhibition of the binding between EF-lα and F-actin.

Keywords: calmodulin; cytoskeletal regulation; elongation factor la; F-actin bundling; Tetrahymena

Journal Article.  0 words. 

Subjects: Biochemistry

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