title: Association of spindle assembly checkpoint component XMAD2 with unattached kinetochores.
abstract: The spindle assembly checkpoint delays anaphase until all chromosomes are attached to a mitotic spindle. The mad (mitotic arrest-deficient) and bub (budding uninhibited by benzimidazole) mutants of budding yeast lack this checkpoint and fail to arrest the cell cycle when microtubules are depolymerized. A frog homolog of MAD2 (XMAD2) was isolated and found to play an essential role in the spindle assembly checkpoint in frog egg extracts. XMAD2 protein associated with unattached kinetochores in prometaphase and in nocodazole-treated cells and disappeared from kinetochores at metaphase in untreated cells, suggesting that XMAD2 plays a role in the activation of the checkpoint by unattached kinetochores. This study furthers understanding of the mechanism of cell cycle checkpoints in metazoa and provides a marker for studying the role of the spindle assembly checkpoint in the genetic instability of tumors.
authors.affiliation: Department of Physiology, University of California, San Francisco, 94143, USA. Chapel Hill, NC 27599, USA.
authors.forename: R H
authors.initials: RH
authors.lastname: Chen
authors.forename: J C
authors.initials: JC
authors.lastname: Waters
authors.forename: E D
authors.initials: ED
authors.lastname: Salmon
authors.forename: A W
authors.initials: AW
authors.lastname: Murray
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002453:Cell Cycle; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D018386:Kinetochores / Q000378:metabolism*; D034882:Lamins; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000737:chemistry; D009687:Nuclear Proteins / Q000378:metabolism; D010063:Ovum; D006656:Protamine Kinase / Q000378:metabolism; D008941:Spindle Apparatus / Q000502:physiology*; D014981:Xenopus
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D034882:Lamins; D009687:Nuclear Proteins; C095122:multidrug resistance protein 3; D006656:Protamine Kinase; D002118:Calcium