Spi1 GTPase interacts with RCC1 to maintain interdependency of cell cycle events

Matsumoto, T., Beach, D. (1991) Spi1 GTPase interacts with RCC1 to maintain interdependency of cell cycle events. Princess Takamatsu Symp, 22. pp. 145-52.

URL: http://www.ncbi.nlm.nih.gov/pubmed/1844237


A mutant which can enter mitosis at any cell cycle stage has been isolated and characterized in fission yeast. The pim1 (premature initiation of mitosis) mutant prearrested at G1/S can develop a mitotic spindle and has tightly condensed chromosomes upon shift to the restrictive temperature. pim1-induced mitosis requires maturation promoting factor (MPF) activity, but not the essential mitotic inducer, cdc25. The pim1+ gene encodes a homolog of regulator of chromosome condensation 1 (RCC1), a regulator of onset of mitosis in mammalian cells. A multicopy suppressor of pim1, spi1, was isolated, and found to encode a 25 kDa GTPase. The primary sequence of the spi1 GTPase shows extensive identity (80%) to human TC4, whose function is unknown. The spi1/TC4 GTPase defines a novel class in the "ras-like" GTPase family, which is distinct from ras, rho, or ypt. Disruption of the spi1+ gene causes genomic instability in a heterozygous diploid. These genetic data suggest that pim1+ and spi1+ interact to coordinate correct entry into mitosis. Immunological experiments demonstrate that the pim1+ and spi1+ products are physically associated. Mutation in the pim1 gene results in lowered affinity of the protein for the spi1 protein in vitro, which may explain why high dosages of the spi1 protein can rescue the pim1 mutant in vivo. The pim1/spi1 complex dissociates in the presence of Mg2+ and GTP. The current data suggests that pim1+ acts as a GTP exchanger for the spi1 GTPase.

Item Type: Paper
Uncontrolled Keywords: Amino Acid Sequence *Cell Cycle *Cell Cycle Proteins DNA-Binding Proteins/*genetics GTP Phosphohydrolases/*genetics *Guanine Nucleotide Exchange Factors Guanosine Triphosphate/metabolism Humans Mitosis Molecular Sequence Data Mutation *Nuclear Proteins Schizosaccharomyces/metabolism
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > GTPase
organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > cell cycle
CSHL Authors:
Communities: CSHL labs > Beach lab
Depositing User: Matt Covey
Date: 1991
Date Deposited: 10 Dec 2015 21:07
Last Modified: 10 Dec 2015 21:07
URI: https://repository.cshl.edu/id/eprint/32150

Actions (login required)

Administrator's edit/view item Administrator's edit/view item
CSHL HomeAbout CSHLResearchEducationNews & FeaturesCampus & Public EventsCareersGiving