Cytokinesis in Tetrahymena: Determination of division plane and organization of contractile ring

Osamu Numata, Kohsuke Gonda, Atsushi Watanabe, Yasuhiro Kurasawa

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


A protein, Tetrahymena p85, is localized to the presumptive division plane before the formation of the contractile ring. p85 directly interacts with Tetrahymena calmodulin (CaM) in a Ca2+-dependent manner, and p85 and CaM colocalize in the division furrow. A Ca2+/CaM inhibitor N-(6- Aminohexyl)-5-chloro-1-naphthalenesulfonamide HCl (W7) inhibits the direct interaction between p85 and Ca2+/CaM. W7 also inhibits the localization of p85 and CaM to the division plane, and the formation of the contractile ring and division furrow. Tetrahymena fimbrin and elongation factor-1a (EF-1α), which induce bundling of Tetrahymena F-actin, are also localized to the division furrow during cytokinesis. The Tetrahymena fimbrin has two actin- binding domains, but lacks the EF-hand Ca2+-binding motif, suggesting that Tetrahymena fimbrin probably crosslinks actin filaments in a Ca2+- insensitive manner during cytokinesis. The evidence also indicates that Ca2+/CaM inhibits the F-actin-bundling activity of EF-1α; and EF-1α and CaM colocalize in the division furrow. In this review, we propose that the Ca2+/CaM signal and its target protein p85 cooperatively regulate the determination of the division plane, and that a Ca2+-insensitive actin- bundling protein, Tetrahymena fimbrin, and a Ca2+/CaM-sensitive actin- bundling protein, EF-1α, play pivotal roles in regulating the organization of the contractile ring microfilaments. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish
Pages (from-to)127-135
Number of pages9
JournalMicroscopy Research and Technique
Issue number2
Publication statusPublished - 2000 Apr 15
Externally publishedYes


  • Actin
  • Ca
  • Calmodulin
  • EF-1α
  • Fimbrin
  • p85

ASJC Scopus subject areas

  • Anatomy
  • Histology
  • Instrumentation
  • Medical Laboratory Technology


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