We have identified a maize homologue of yeast MAD2, an essential component in the spindle checkpoint pathway that ensures metaphase is complete before anaphase begins. Combined immunolocalization of MAD2 and a recently cloned maize CENPC homologue indicates that MAD2 localizes to an outer domain of the prometaphase kinetochore. MAD2 staining was primarily observed on mitotic kinetochores that lacked attached microtubules; i.e., at prometaphase or when the microtubules were depolymerized with oryzalin. In contrast, the loss of MAD2 staining in meiosis was not correlated with initial microtubule attachment but was correlated with a measure of tension: the distance between homologous or sister kinetochores (in meiosis I and II, respectively). Further, the tension-sensitive 3F3/2 phosphoepitope colocalized, and was lost concomitantly, with MAD2 staining at the meiotic kinetochore. The mechanism of spindle assembly (discussed here with respect to maize mitosis and meiosis) is likely to affect the relative contributions of attachment and tension. We support the idea that MAD2 is attachment-sensitive and that tension stabilizes microtubule attachments.
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3 May 1999
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May 03 1999
The Maize Homologue of the Cell Cycle Checkpoint Protein MAD2 Reveals Kinetochore Substructure and Contrasting Mitotic and Meiotic Localization Patterns
Hong-Guo Yu,
Hong-Guo Yu
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
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Michael G. Muszynski,
Michael G. Muszynski
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
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R. Kelly Dawe
R. Kelly Dawe
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
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Hong-Guo Yu
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
Michael G. Muszynski
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
R. Kelly Dawe
*Department of Botany and ‡Department of Genetics, University of Georgia, Athens, Georgia 30602; §Pioneer Hi-Bred International, Inc., Johnston, Iowa 50131
Address correspondence to R. Kelly Dawe, Department of Botany, Miller Plant Sciences Bldg., University of Georgia, Athens, GA 30602. Tel.: (706) 542-1658. Fax: (706) 542-1805. E-mail: [email protected]
Received:
January 08 1999
Revision Received:
March 22 1999
Online ISSN: 1540-8140
Print ISSN: 0021-9525
1999
J Cell Biol (1999) 145 (3): 425–435.
Article history
Received:
January 08 1999
Revision Received:
March 22 1999
Citation
Hong-Guo Yu, Michael G. Muszynski, R. Kelly Dawe; The Maize Homologue of the Cell Cycle Checkpoint Protein MAD2 Reveals Kinetochore Substructure and Contrasting Mitotic and Meiotic Localization Patterns . J Cell Biol 3 May 1999; 145 (3): 425–435. doi: https://doi.org/10.1083/jcb.145.3.425
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