Abstract
We have shown previously that Ipl1 and Sli15 are required for chromosome segregation in Saccharomyces cerevisiae. Sli15 associates directly with the Ipl1 protein kinase and these two proteins colocalize to the mitotic spindle. We show here that Sli15 stimulates the in vitro, and likely in vivo, kinase activity of Ipl1, and Sli15 facilitates the association of Ipl1 with the mitotic spindle. The Ipl1-binding and -stimulating activities of Sli15 both reside within a region containing homology to the metazoan inner centromere protein (INCENP). Ipl1 and Sli15 also bind to Dam1, a microtubule-binding protein required for mitotic spindle integrity and kinetochore function. Sli15 and Dam1 are most likely physiological targets of Ipl1 since Ipl1 can phosphorylate both proteins efficiently in vitro, and the in vivo phosphorylation of both proteins is reduced in ipl1 mutants. Some dam1 mutations exacerbate the phenotype of ipl1 and sli15 mutants, thus providing evidence that Dam1 interactions with Ipl1-Sli15 are functionally important in vivo. Similar to Dam1, Ipl1 and Sli15 each bind to microtubules directly in vitro, and they are associated with yeast centromeric DNA in vivo. Given their dual association with microtubules and kinetochores, Ipl1, Sli15, and Dam1 may play crucial roles in regulating chromosome-spindle interactions or in the movement of kinetochores along microtubules.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Aurora Kinases
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Fractionation
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Chromosomal Proteins, Non-Histone / metabolism*
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Chromosomes / metabolism
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Cytoskeletal Proteins / metabolism
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Green Fluorescent Proteins
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Indicators and Reagents / metabolism
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Intracellular Signaling Peptides and Proteins
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Luminescent Proteins / metabolism
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism*
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Microtubules / metabolism
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Phosphorylation
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Protein Serine-Threonine Kinases
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
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Spindle Apparatus / metabolism
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Two-Hybrid System Techniques
Substances
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Cell Cycle Proteins
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Chromosomal Proteins, Non-Histone
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Cytoskeletal Proteins
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DAM1 protein, S cerevisiae
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DUO1 protein, S cerevisiae
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Indicators and Reagents
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Intracellular Signaling Peptides and Proteins
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Luminescent Proteins
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Microtubule-Associated Proteins
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Green Fluorescent Proteins
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Protein Kinases
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Aurora Kinases
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IPL1 protein, S cerevisiae
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Protein Serine-Threonine Kinases