Dynamic attachment of microtubules to kinetochores during mitosis generates pulling force, or tension, required for the high fidelity of chromosome separation. A lack of tension activates the spindle checkpoint and delays the anaphase onset. A key step in the tension–response pathway involves the phosphorylation of the 3F3/2 epitope by an unknown kinase on untensed kinetochores. Using a rephosphorylation assay in Xenopus laevis extracts, we identified the kinetochore-associated Polo-like kinase Plx1 as the kinase both necessary and sufficient for this phosphorylation. Indeed, Plx1 is the physiological 3F3/2 kinase involved in checkpoint response, as immunodepletion of Plx1 from checkpoint extracts abolished the 3F3/2 signal and blocked association of xMad2, xBubR1, xNdc80, and xNuf2 with kinetochores. Interestingly, the kinetochore localization of Plx1 is under the control of the checkpoint protein xMps1, as immunodepletion of xMps1 prevents binding of Plx1 to kinetochores. Thus, Plx1 couples the tension signal to cellular responses through phosphorylating the 3F3/2 epitope and targeting structural and checkpoint proteins to kinetochores.
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29 August 2005
Article|
August 29 2005
Plx1 is the 3F3/2 kinase responsible for targeting spindle checkpoint proteins to kinetochores
Oi Kwan Wong,
Oi Kwan Wong
Department of Biological Sciences, Stanford University, Stanford, CA 94305
Search for other works by this author on:
Guowei Fang
Guowei Fang
Department of Biological Sciences, Stanford University, Stanford, CA 94305
Search for other works by this author on:
Oi Kwan Wong
Department of Biological Sciences, Stanford University, Stanford, CA 94305
Guowei Fang
Department of Biological Sciences, Stanford University, Stanford, CA 94305
Correspondence to Guowei Fang: [email protected]
Abbreviations used in this paper: APC/C, anaphase-promoting complex/cyclosome; CSF, cytostatic factor; NEM, N-ethyl maleimide; Plx1-KD, Plx1 kinase-dead mutant; RNAi, RNA interference; siRNA, small interfering RNA; xMps1-KD, xMps1 kinase-dead mutant; XTC, Xenopus laevis tissue culture.
Received:
February 28 2005
Accepted:
July 25 2005
Online ISSN: 1540-8140
Print ISSN: 0021-9525
The Rockefeller University Press
2005
J Cell Biol (2005) 170 (5): 709–719.
Article history
Received:
February 28 2005
Accepted:
July 25 2005
Citation
Oi Kwan Wong, Guowei Fang; Plx1 is the 3F3/2 kinase responsible for targeting spindle checkpoint proteins to kinetochores . J Cell Biol 29 August 2005; 170 (5): 709–719. doi: https://doi.org/10.1083/jcb.200502163
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