Abstract
For chromosomes to congress and segregate during cell division, kinetochores must form stable attachments with spindle microtubules. We find that the centrosome protein, xCep57, localizes to kinetochores and interacts with the kinetochore proteins Zwint, Mis12, and CLIP-170. Immunodepletion of xCep57 from egg extracts yields weakened and elongated bipolar spindles which fail to align chromosomes. In the absence of xCep57, tension is lost between sister kinetochores, and spindle microtubules are no longer resistant to low doses of nocodazole. xCep57 inhibition on isolated mitotic chromosomes inhibits kinetochore-microtubule binding in vitro. xCep57 also interacts with gamma-tubulin. In xCep57 immunodepleted extracts, sperm centrosomes nucleate with normal kinetics, but are unable maintain microtubule anchorage. This characterization places xCep57 in a novel class of proteins required for stable microtubule attachments at the kinetochore and at the centrosome and suggests that the mechanism of microtubule binding at these two places is mechanistically similar.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antimitotic Agents / pharmacology
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Carrier Proteins / chemistry
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Cell Cycle Proteins
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Centrosome / metabolism
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Kinetics
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Kinetochores / drug effects
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Kinetochores / metabolism*
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Male
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Metaphase / physiology
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Microtubule-Associated Proteins / chemistry
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism*
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Microtubules / drug effects
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Microtubules / metabolism*
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Mitosis / drug effects
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Mitosis / physiology*
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Molecular Weight
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Neoplasm Proteins / metabolism
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Nocodazole / pharmacology
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Sequence Analysis, Protein
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Sequence Homology, Amino Acid
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Spermatozoa / metabolism
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Spindle Apparatus / drug effects
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Spindle Apparatus / metabolism*
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Tubulin / metabolism
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Xenopus Proteins / chemistry
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Xenopus Proteins / genetics
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Xenopus Proteins / metabolism*
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Xenopus laevis
Substances
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Antimitotic Agents
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Carrier Proteins
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Cell Cycle Proteins
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Microtubule-Associated Proteins
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Neoplasm Proteins
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Nuclear Proteins
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Tsp57 protein, mouse
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Tubulin
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Xenopus Proteins
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cytoplasmic linker protein 170
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Nocodazole