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Cytokinesis in Tetrahymena : Determination of division plane and organization of contractile ring
Author(s) -
Numata Osamu,
Gonda Kohsuke,
Watanabe Atsushi,
Kurasawa Yasuhiro
Publication year - 2000
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/(sici)1097-0029(20000415)49:2<127::aid-jemt4>3.0.co;2-k
Subject(s) - cytokinesis , tetrahymena , microbiology and biotechnology , colocalization , cell division , actin , biology , cleavage furrow , microfilament , calmodulin , cell plate , cytoskeleton , cell , biochemistry , enzyme
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 Ca 2+ ‐dependent manner, and p85 and CaM colocalize in the division furrow. A Ca 2+ /CaM inhibitor N‐(6‐Aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide HCl (W7) inhibits the direct interaction between p85 and Ca 2+ /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 Ca 2+ ‐binding motif, suggesting that Tetrahymena fimbrin probably cross‐links actin filaments in a Ca 2+ ‐ insensitive manner during cytokinesis. The evidence also indicates that Ca 2+ /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 Ca 2+ /CaM signal and its target protein p85 cooperatively regulate the determination of the division plane, and that a Ca 2+ ‐insensitive actin‐bundling protein, Tetrahymena fimbrin, and a Ca 2+ /CaM‐sensitive actin‐bundling protein, EF‐1α, play pivotal roles in regulating the organization of the contractile ring microfilaments. Microsc. Res. Tech. 49:127–135, 2000. © 2000 Wiley‐Liss, Inc.