Localization of the Drosophila checkpoint control protein Bub3 to the kinetochore requires Bub1 but not Zw10 or Rod |
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Authors: | Joydeep Basu Elsa Logarinho Siegrun Herrmann Hassan Bousbaa ZeXiao Li Gordon K T Chan Tim J Yen Claudio E Sunkel Michael L Goldberg |
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Institution: | (1) Section of Genetics and Development, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA, US;(2) Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, P-4150 Porto, Portugal, PT;(3) The Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA, US;(4) Instituto de Abel Salazar, Universidade do Porto, Largo do Prof. Abel Salazar 2, P-4050 Porto, Portugal, PT |
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Abstract: | We report here the isolation and molecular characterization of the Drosophila homolog of the mitotic checkpoint control protein Bub3. The Drosophila Bub3 protein is associated with the centromere/kinetochore of chromosomes in larval neuroblasts whose spindle assembly checkpoints
have been activated by incubation with the microtubule-depolymerizing agent colchicine. Drosophila Bub3 is also found at the kinetochore regions in mitotic larval neuroblasts and in meiotic primary and secondary spermatocytes,
with the strong signal seen during prophase and prometaphase becoming increasingly weaker after the chromosomes have aligned
at the metaphase plate. We further show that the localization of Bub3 to the kinetochore is disrupted by mutations in the
gene encoding the Drosophila homolog of the spindle assembly checkpoint protein Bub1. Combined with recent findings showing that the kinetochore localization
of Bub1 conversely depends upon Bub3, these results support the hypothesis that the spindle assembly checkpoint proteins exist
as a multiprotein complex recruited as a unit to the kinetochore. In contrast, we demonstrate that the kinetochore constituents
Zw10 and Rod are not needed for the binding of Bub3 to the kinetochore. This suggests that the kinetochore is assembled in
at least two relatively independent pathways.
Received: 6 August 1998 / Accepted: 28 August 1998 |
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