Cytokinesis in budding yeast involves an actomyosin-based ring which assembles in a multistepped fashion during the cell cycle and constricts during cytokinesis. In this report, we have investigated the structural and regulatory events that occur at the onset of cytokinesis. The septins, which form an hour-glass like structure during early stages of the cell cycle, undergo dynamic rearrangements prior to cell division: the hourglass structure splits into two separate rings. The contractile ring, localized between the septin double rings, immediately undergoes contraction. Septin ring splitting is independent of actomyosin ring contraction as it still occurs in mutants where contraction fails. We hypothesize that septin ring splitting may remove a structural barrier for actomyosin ring to contract. Because the Tem1 small GTPase (Tem1p) is required for the completion of mitosis, we investigated its role in regulating septin and actomyosin ring dynamics in the background of the net1-1 mutation, which bypasses the anaphase cell cycle arrest in Tem1-deficient cells. We show that Tem1p plays a specific role in cytokinesis in addition to its function in cell cycle progression. Tem1p is not required for the assembly of the actomyosin ring but controls actomyosin and septin dynamics during cytokinesis.


Biological Sciences

Keywords and Phrases

Guanosine Triphosphatase; Myosin Adenosine Triphosphatase; Septin; Anaphase; Cell Cycle; Cell Division; Controlled Study; Cytokinesis; Enzyme Activity; Gene Control; Gene Mutation; Gene Rearrangement; Gene Structure; Mitosis; Molecular Dynamics; Nonhuman; Actomyosin; Fungal Proteins; Monomeric GTP-Binding Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Saccharomycetales; Budding Yeast; Cytokinesis; GTPase; Temp1p

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

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© 2001 Company of Biologists Ltd, All rights reserved.

Publication Date

01 Jan 2001

PubMed ID


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Biology Commons